[Feat]: Support EC public key

[giovannipapini]

Is your feature request related to a problem? Please describe.

Currently, trying to integrate auth login with external server bearer token, I receive this error

{"level":"panic","error":"Key is not a valid RSA public key","goroutine":1,"caller":"zotregistry.dev/zot/pkg/api/authn.go:426","time":"2024-08-03T13:52:30.053939244Z","message":"failed to create bearer authorizer"}

because it seems that Zot does not support EC (not RSA) public keys.

Describe the solution you'd like

No response

Describe alternatives you've considered

No response

Additional context

No response

[rchincha]

@giovannipapini we use chart-museum as our library for this, which currently supports only RSA. Let us look into this.