Refactor key generation classes #961

Job	Run time
Windows-2022 [arch x64, toolset v143, backend botan, build shared libs off, use CMake prefix path on, sanitizers off]	1m 55s
Windows-2022 [arch x64, toolset v143, backend botan, build shared libs off, use CMake prefix path off, sanitizers off]	2m 8s
Windows-2022 [arch x64, toolset v143, backend openssl, build shared libs off, use CMake prefix path on, sanitizers off]	1m 51s
Windows-2022 [arch x64, toolset v143, backend openssl, build shared libs off, use CMake prefix path off, sanitizers off]	1m 50s
Windows-2022 [arch x64, toolset ClangCL, backend botan, build shared libs off, use CMake prefix path on, sanitizers off]	2m 59s
Windows-2022 [arch x64, toolset ClangCL, backend botan, build shared libs off, use CMake prefix path off, sanitizers off]	5m 1s
Windows-2022 [arch x64, toolset ClangCL, backend openssl, build shared libs off, use CMake prefix path on, sanitizers off]	2m 50s
Windows-2022 [arch x64, toolset ClangCL, backend openssl, build shared libs off, use CMake prefix path off, sanitizers off]	3m 35s
Windows-2022 [arch x64, toolset v143, backend botan, build shared libs off, use CMake prefix path off, sanitizers on]	2m 7s
Windows-2022 [arch Win32, toolset ClangCL, backend botan, build shared libs off, use CMake prefix path on, sanitizers off]	6m 24s
Windows-2022 [arch Win32, toolset v143, backend openssl, build shared libs off, use CMake prefix path off, sanitizers off]	5m 43s
	36m 23s

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