Do not load duplicate certs in ChipCertificateSet

[pan-apple]

Problem

The certificate loading fails after a few tries when the same cert is loaded repeatedly.

Change overview

The ChipCertificateSet::LoadCert doesn't check if the cert (being loaded) is already present in the certificate set. It parses it and adds it to the set. The current limit of certs in a set is set to 4 (3 in tests). This PR adds a new method to ChipCertificateData to compare two certificates. The LoadCert() loads the certificate in a temporary ChipCertificateData instance, and compares it to the existing certs. If the cert is not found, it gets copied to one of the available slot in the set. If the set has no available slot, the function will return error.

Testing

Added a new unit test TestChipCert_LoadDuplicateCerts to test this behavior.
The rest of TestChipCert test suite ensures no existing functionality is broken.

[github-actions]

Size increase report for "gn_qpg6100-example-build" from 764df83

File	Section	File	VM
chip-qpg6100-lighting-example.out	.text	336	336

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-qpg6100-lighting-example.out.map and ./pull_artifact/chip-qpg6100-lighting-example.out.map:

BLOAT EXECUTION FAILED WITH CODE 1:
bloaty: unknown file type for file './pull_artifact/chip-qpg6100-lighting-example.out.map'

Comparing ./master_artifact/chip-qpg6100-lighting-example.out and ./pull_artifact/chip-qpg6100-lighting-example.out:

sections,vmsize,filesize
.debug_info,0,3102
.debug_loc,0,597
.text,336,336
.debug_str,0,68
.debug_line,0,62
.strtab,0,58
.debug_ranges,0,48
.symtab,0,32
.debug_frame,0,28
.debug_abbrev,0,23
.debug_aranges,0,8
.shstrtab,0,-2
[Unmapped],0,-336

[github-actions]

Size increase report for "nrfconnect-example-build" from 764df83

File	Section	File	VM
chip-lock.elf	text	324	324
chip-lock.elf	device_handles	-4	-4

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-lock.elf and ./pull_artifact/chip-lock.elf:

sections,vmsize,filesize
.debug_info,0,3160
.debug_loc,0,706
text,324,324
.debug_line,0,87
.debug_str,0,62
.strtab,0,58
.debug_ranges,0,56
.debug_abbrev,0,37
.symtab,0,32
.debug_frame,0,28
.debug_aranges,0,8
.shstrtab,0,-2
device_handles,-4,-4

Comparing ./master_artifact/chip-shell.elf and ./pull_artifact/chip-shell.elf:

sections,vmsize,filesize
.debug_info,0,504
.debug_str,0,58
.debug_loc,0,-66

[github-actions]

Size increase report for "esp32-example-build" from 764df83

File	Section	File	VM
chip-all-clusters-app.elf	.flash.text	328	328

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-pigweed-app.elf and ./pull_artifact/chip-pigweed-app.elf:

sections,vmsize,filesize

Comparing ./master_artifact/chip-all-clusters-app.elf and ./pull_artifact/chip-all-clusters-app.elf:

sections,vmsize,filesize
.debug_info,0,3813
.flash.text,328,328
.debug_loc,0,275
.debug_line,0,264
.debug_str,0,67
.strtab,0,58
.debug_frame,0,24
.debug_ranges,0,24
.symtab,0,16
.debug_aranges,0,8
.xt.prop._ZTVN4chip11DeviceLayer37DeviceNetworkProvisioningDelegateImplE,0,1
.shstrtab,0,-2

[todo]

- Add an operator== on BitFlags class.

connectedhomeip/src/credentials/CHIPCert.cpp

Lines 617 to 627 in 9dddc28

	// TODO - Add an operator== on BitFlags class.
	return mSubjectDN.IsEqual(other.mSubjectDN) && mIssuerDN.IsEqual(other.mIssuerDN) &&
	mSubjectKeyId.IsEqual(other.mSubjectKeyId) && mAuthKeyId.IsEqual(other.mAuthKeyId) &&
	(mNotBeforeTime == other.mNotBeforeTime) && (mNotAfterTime == other.mNotAfterTime) &&
	(mPublicKeyLen == other.mPublicKeyLen) && (memcmp(mPublicKey, other.mPublicKey, mPublicKeyLen) == 0) &&
	(mPubKeyCurveOID == other.mPubKeyCurveOID) && (mPubKeyAlgoOID == other.mPubKeyAlgoOID) &&
	(mSigAlgoOID == other.mSigAlgoOID) && (mCertFlags.Raw() == other.mCertFlags.Raw()) &&
	(mKeyUsageFlags.Raw() == other.mKeyUsageFlags.Raw()) && (mKeyPurposeFlags.Raw() == other.mKeyPurposeFlags.Raw()) &&
	(mPathLenConstraint == other.mPathLenConstraint) && (mSignature.RLen == other.mSignature.RLen) &&
	(memcmp(mSignature.R, other.mSignature.R, mSignature.RLen) == 0) && (mSignature.SLen == other.mSignature.SLen) &&
	(memcmp(mSignature.S, other.mSignature.S, mSignature.SLen) == 0) &&

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This comment was generated by todo based on a TODO comment in 9dddc28 in #7115. cc @pan-apple.