Machine Identity: Keys management & signing SPIFFE JWT-SVID node identities

[prbinu-nvidia]

Track the signing component in the Carbide api server that implements the signing JWT-SVIDs, key management and JWKS/SPIFFE-bundle distribution.

sub tasks:

1. key pair generation for tenants
2. encryption (with master-key) of private key used to sign JWT-SVID
3. master key storage/mgmt
4. signing of identity requests
5. JWKS distribution APIs