App layer crypto codec

[hulto]

What type of PR is this?

/kind feature

What this PR does / why we need it:

• Adds a custom codec to encrypt the grpc protocol with xchacha20-poly1305
• Derives a shared key between the server and client by using a diffie hellman key exchange
• Adds a secrets manager (gcp for prod, yaml file on disk for dev)
• Stores the server private key in the secrets manager
• Creates a more locked down service account for cloud run (roles/logging.logWriter, roles/monitoring.metricWriter, roles/cloudsql.client, and roles/secretmanager.secretAccessor@REALM_tavern_encryption_private_key

TODO

• Add secrets management interface
• Add secrets impl as a file on disk for debug builds
• Add GCP Secrets manager to Terraform
• Add secrets impl in GCP HSM
• Store crypto private key with secrets management interface
• Prevent VScode from throwing lint warnings about env!
• Update docs
• Cleanup

Which issue(s) this PR fixes:

[hulto]

An error (new to me) seems to occur intermittently

Hasn't been an issue the last four commits.
Could have been an issue in the github actions env the other day.