Move actual key store into Mock BPA

[BrianSipos]

This resolves #245 by moving the demo key store into the Mock BPA proper and providing a key store callback interface in the crypto library.

[BrianSipos]

This is a somewhat messy refactoring, so I expect that several symbol names will need to be fixed after moving things around.

[BrianSipos]

@250MHz as of now, the callback interface in bsl/crypto/KeyStore.h is for the crypto functions reading key info but not modifying it. If there is value in moving the JWK Set and COSE_KeySet readers into the common crypto library, the callbacks can be augmented for adding key and setting key parameter.

[sonarqubecloud]

Quality Gate passed

Issues
8 New issues
0 Accepted issues

Measures
0 Security Hotspots
76.6% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[250MHz]

If there is value in moving the JWK Set and COSE_KeySet readers into the common crypto library, the callbacks can be augmented for adding key and setting key parameter.

I think BPAs would find that helpful, but might be nicer from BSL's POV for the readers to be in a separate library from libbsl_crypto?