Update proto definitions for custom bitbucket oauth

[casey-tran]

Description:

Update the proto definitions found for Bitbucket sources to have OAuth option in the config file. Also regenerated the Protobuf files with the changes.

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?

[martinlocklear]

Approving to unblock, but it would be nice if there was some inline documentation here about what these fields are for. The commit message also isn't entirely accurate right? Seems like you're adding fields and regenerating protos.