Migrate to pydantic-based local configuration schema

[achimnol]

Along with #2760, we found that there is a deviation between wsproxy and other server packages: pydantic-based vs. trafaret-based local-config schema.

Let's migrate our local configs to pydantic.

• Prerequisite: Split out ai.backend.typeutils and ai.backend.types packages.
• Migrate ai.backend.logging.config to use pydantic-based schema as well.
• wsproxy.cli.context.CLIContext: Let it respect the local logging configuration if present and silently fallback to a default config like other server components. (remaining of Wrong Implicit log level overridding when --log-level argument is not provided #2759)
• Rewrite all local config schema of other server packages like wsproxy.