`DatabaseAttestationSourceValidator` could validate datasource

[ndr-brt]

Feature Request

Currently, if there's an error in the configuration of the database attestation (e.g. unexisting datasource or table) that will be caught only during the credential issuance flow, while it could be validated directly in the DatabaseAttestationSourceValidator so the attestation creation will fail straight away

Which Areas Would Be Affected?

e.g., DPF, CI, build, transfer, etc.

Why Is the Feature Desired?

Are there any requirements?

Who will sponsor this feature?

Please @-mention the committer that will sponsor your feature.

Solution Proposal

If possible, provide a (brief!) solution proposal.

[github-actions]

This issue is stale because it has been open for 14 days with no activity.