KMS key versionless support

[lzhecheng]

Describe the request

With this feature, kms users can choose to not specify key version, instead the kms plugin gets latest key version from akv.

Explain why KMS Plugin for Key Vault needs it

It reduces users' effort when they need to rotate key regularly.

Describe the solution you'd like

Kms plugin retrieves latest key version when encryption and puts it into annotation. When decryption, kms plugin retrieves key version from annotation and uses it to decrypt.

Describe alternatives you've considered

Additional context

POC code

[lzhecheng]

Cache design for getting latest key version also need consideration.