cloud secrets storage

[airbyte-jenny]

• Secrets Handling Tech Spec #5505
• use spec when persisting source configs #6036
• Interface changes to support separating secrets from the config #6065
• separate mechanism for writing configs to Google Secrets Manager #6105
• define structure for partial secret configs / coordinate usage  #6099
• expose partial secret configs from the config repo #6100
• access secrets from store from the workers instead of the config repo #6101
• handle any misc endpoints (will create tickets for these)
• handle secret versioning exposure
• ensure proper oauth integration
• set up GSM on cloud projects in a scripted / repeatable way (if it's not possible in terraform) #6106
• set up migration process for cloud to move secrets into GSM #6107
• integration testing with secrets storage #6108
• make sure this is feature-flaggable behavior without migrations

[jrhizor]

Current state is that secrets storage is configured and in use on all environments for cloud.

We still have to release #6654 and migrate existing configs to it, and there are various cleanups around how we handle OAuth vs user secrets, better permissions for secrets, tracking of secret usage, remove stale/unused secrets, etc. We will create followup tickets.