suppress warnings about deprecated fields and enum values

The source protos (or discovery docs) may have deprecated fields, enum values, enums, methods, or even full services.

We carry the deprecation annotations to the Swift code, so our customers can receive a warning if they use the deprecated things.

Our generated code also uses these values and fields, in case we receive them from the wire, or somebody uses them.

The latter usage produces warnings. I would like to suppress these warnings.

The issue does not name a file or test; start by locating the generated Swift code that references deprecated fields, enum values, enums, methods, or services, and identify how deprecation annotations are emitted. Confirm the current compiler warnings and determine how generated-code usage can be suppressed without removing customer-facing deprecation warnings. Done means those internal warnings no longer appear while deprecated API use still warns customers.

Written by the indexing model from the issue text.