Fix octetStringEscapedForCLiteral to handle non-ASCII better.

[bzbarsky-apple]

There were several bugs in octetStringEscapedForCLiteral:

1. It used \x escapes, but decimal charcode numbers. Since it was
   only tested for charcode 0, this was not obvious.
2. It did not escape '"', which could break things.
3. It did not escape non-control non-ASCII characters (anything with
   charcode > 127).

As a result the string "\r\n\xff"\xa0" in YAML would get represented
in the C++ as:

"\x13\x10ÿ" "

and after this change is represented as:

"\x0d\x0a\xff\x22\xa0"

Problem

See above.

Change overview

See above.

Testing

Hard to test the test harness.... Manual inspection of the generated code, plus the fact that the embedded " now doesn't cause compiler errors.

[github-actions]

PR #13138: Size comparison from 7283e3a to 5e8be22

Increases (1 build for linux)

platform	target	config	section	7283e3a	5e8be22	change	% change
linux	chip-tool-ipv6only	arm64	(read only)	6977548	6979164	1616	0.0
			(read/write)	325601	325633	32	0.0
			.got	56504	56536	32	0.1
			.rodata	383540	383732	192	0.1
			.text	5902212	5903540	1328	0.0

Full report (31 builds for efr32, esp32, k32w, linux, mbed, nrfconnect, p6, qpg, telink)

platform	target	config	section	7283e3a	5e8be22	change	% change
efr32	lighting-app	BRD4161A	(read only)	830584	830584	0	0.0
			(read/write)	127360	127360	0	0.0
			.bss	125480	125480	0	0.0
			.data	1876	1876	0	0.0
			.text	830576	830576	0	0.0
		BRD4161A+rpc	(read only)	818212	818212	0	0.0
			(read/write)	144024	144024	0	0.0
			.bss	142048	142048	0	0.0
			.data	1976	1976	0	0.0
			.text	818204	818204	0	0.0
	window-app	BRD4161A	(read only)	803960	803960	0	0.0
			(read/write)	126296	126296	0	0.0
			.bss	124464	124464	0	0.0
			.data	1832	1832	0	0.0
			.text	803952	803952	0	0.0
esp32	all-clusters-app	c3devkit	(read only)	881266	881266	0	0.0
			(read/write)	1312402	1312402	0	0.0
			.dram0.bss	69296	69296	0	0.0
			.dram0.data	14220	14220	0	0.0
			.flash.rodata	175832	175832	0	0.0
			.flash.text	881266	881266	0	0.0
			.iram0.text	62254	62254	0	0.0
		m5stack	(read only)	941919	941919	0	0.0
			(read/write)	441516	441516	0	0.0
			.dram0.bss	73792	73792	0	0.0
			.dram0.data	34056	34056	0	0.0
			.flash.rodata	202660	202660	0	0.0
			.flash.text	936535	936535	0	0.0
			.iram0.text	122671	122671	0	0.0
k32w	light	k32w061+release	(read/write)	648852	648852	0	0.0
			.bss	76488	76488	0	0.0
			.data	1904	1904	0	0.0
			.text	564660	564660	0	0.0
	lock	k32w061+release	(read/write)	633568	633568	0	0.0
			.bss	76208	76208	0	0.0
			.data	1860	1860	0	0.0
			.text	549700	549700	0	0.0
linux	chip-tool-ipv6only	arm64	(read only)	6977548	6979164	1616	0.0
			(read/write)	325601	325633	32	0.0
			.bss	54593	54593	0	0.0
			.data	1096	1096	0	0.0
			.data.rel.ro	209704	209704	0	0.0
			.dynamic	560	560	0	0.0
			.got	56504	56536	32	0.1
			.init	24	24	0	0.0
			.init_array	168	168	0	0.0
			.rodata	383540	383732	192	0.1
			.text	5902212	5903540	1328	0.0
	thermostat-no-ble	arm64	(read only)	2006052	2006052	0	0.0
			(read/write)	144065	144065	0	0.0
			.bss	64353	64353	0	0.0
			.data	880	880	0	0.0
			.data.rel.ro	72088	72088	0	0.0
			.dynamic	560	560	0	0.0
			.got	3840	3840	0	0.0
			.init	24	24	0	0.0
			.init_array	296	296	0	0.0
			.rodata	128356	128356	0	0.0
			.text	1666032	1666032	0	0.0
mbed	all-clusters-app	CY8CPROTO_062_4343W+release	(read only)	6224	6224	0	0.0
			(read/write)	2337920	2337920	0	0.0
			.bss	188580	188580	0	0.0
			.data	5264	5264	0	0.0
			.text	1300496	1300496	0	0.0
	lighting-app	CY8CPROTO_062_4343W+release	(read only)	6224	6224	0	0.0
			(read/write)	2330760	2330760	0	0.0
			.bss	180920	180920	0	0.0
			.data	5552	5552	0	0.0
			.text	1293360	1293360	0	0.0
	lock-app	CY8CPROTO_062_4343W+release	(read only)	6224	6224	0	0.0
			(read/write)	2303792	2303792	0	0.0
			.bss	179968	179968	0	0.0
			.data	5544	5544	0	0.0
			.text	1266392	1266392	0	0.0
	pigweed-app	CY8CPROTO_062_4343W+release	(read only)	6224	6224	0	0.0
			(read/write)	1140008	1140008	0	0.0
			.bss	11756	11756	0	0.0
			.data	4368	4368	0	0.0
			.text	103392	103392	0	0.0
	shell	CY8CPROTO_062_4343W+release	(read only)	6224	6224	0	0.0
			(read/write)	2053688	2053688	0	0.0
			.bss	156972	156972	0	0.0
			.data	4864	4864	0	0.0
			.text	1016288	1016288	0	0.0
nrfconnect	lighting-app	nrf52840dk_nrf52840	(read/write)	936111	936111	0	0.0
			bss	118408	118408	0	0.0
			rodata	108124	108124	0	0.0
			text	632008	632008	0	0.0
		nrf52840dk_nrf52840+rpc	(read/write)	922479	922479	0	0.0
			bss	115452	115452	0	0.0
			rodata	101540	101540	0	0.0
			text	627320	627320	0	0.0
		nrf5340dk_nrf5340_cpuapp	(read/write)	859842	859842	0	0.0
			bss	116692	116692	0	0.0
			rodata	103048	103048	0	0.0
			text	559452	559452	0	0.0
	lock-app	nrf52840dk_nrf52840	(read/write)	908223	908223	0	0.0
			bss	117596	117596	0	0.0
			rodata	103428	103428	0	0.0
			text	609836	609836	0	0.0
		nrf5340dk_nrf5340_cpuapp	(read/write)	832186	832186	0	0.0
			bss	115908	115908	0	0.0
			rodata	98392	98392	0	0.0
			text	537316	537316	0	0.0
	pigweed-app	nrf52840dk_nrf52840	(read/write)	542351	542351	0	0.0
			bss	52588	52588	0	0.0
			rodata	50668	50668	0	0.0
			text	376892	376892	0	0.0
	pump-app	nrf52840dk_nrf52840	(read/write)	909519	909519	0	0.0
			bss	117356	117356	0	0.0
			rodata	103644	103644	0	0.0
			text	611072	611072	0	0.0
	pump-controller-app	nrf52840dk_nrf52840	(read/write)	906335	906335	0	0.0
			bss	117384	117384	0	0.0
			rodata	102900	102900	0	0.0
			text	608584	608584	0	0.0
	shell	nrf52840dk_nrf52840	(read/write)	796079	796079	0	0.0
			bss	109464	109464	0	0.0
			rodata	78096	78096	0	0.0
			text	532048	532048	0	0.0
		nrf5340dk_nrf5340_cpuapp	(read/write)	708710	708710	0	0.0
			bss	107352	107352	0	0.0
			rodata	72396	72396	0	0.0
			text	449544	449544	0	0.0
p6	all-clusters-app	default	(read/write)	2390040	2390040	0	0.0
			.bss	116780	116780	0	0.0
			.data	2544	2544	0	0.0
			.text	1348304	1348304	0	0.0
	light-app	default	(read/write)	2325120	2325120	0	0.0
			.bss	106160	106160	0	0.0
			.data	2384	2384	0	0.0
			.text	1283384	1283384	0	0.0
	lock-app	default	(read/write)	2297328	2297328	0	0.0
			.bss	105040	105040	0	0.0
			.data	2336	2336	0	0.0
			.text	1255592	1255592	0	0.0
qpg	lighting-app	qpg6105+debug	(read only)	532352	532352	0	0.0
			(read/write)	146936	146936	0	0.0
			.bss	86824	86824	0	0.0
			.data	1004	1004	0	0.0
			.text	527032	527032	0	0.0
	lock-app	qpg6105+debug	(read only)	504016	504016	0	0.0
			(read/write)	146940	146940	0	0.0
			.bss	85960	85960	0	0.0
			.data	952	952	0	0.0
			.text	498696	498696	0	0.0
	persistent-storage-app	qpg6105+debug	(read only)	106448	106448	0	0.0
			(read/write)	146938	146938	0	0.0
			.bss	36146	36146	0	0.0
			.data	288	288	0	0.0
			.text	101128	101128	0	0.0
telink	lighting-app	tlsr9518adk80d	(read/write)	832370	832370	0	0.0
			bss	87064	87064	0	0.0
			noinit	37160	37160	0	0.0
			text	580500	580500	0	0.0