Add OTLP ingest feature

[mx-psi]

What does this PR do?

Add otlp feature to configure OTLP ingest.

Motivation

Allow users to configure this feature via the Datadog operator.

Additional Notes

Configuration has the same schema as DataDog/helm-charts/pull/619. This is slightly different from the Agent's, since it has the enabled flags explicitly.

As it happens in the Helm chart, this PR only adds support for defining an OTLP/gRPC endpoint with a host and port, and not via a Unix socket.

Describe your test plan

Test the Datadog operator with the following test cases:

• [ ] Setting the gRPC endpoint to unix:/path/to/socket.sock results in an error
• [ ] Setting the gRPC endpoint to unix-abstract:opaquedata results in an error
• [ ] Setting the gRPC endpoint to 0.0.0.0 results in an error
• [ ] Setting the HTTP endpoint to 0.0.0.0 results in an error
• [ ] Setting both endpoints with an explicit port works correctly.
• [ ] Only setting gRPC endpoint works correctly.
• [ ] Only setting HTTP endpoint works correctly.
• [ ] Setting the gRPC section with enabled:true and no endpoint works with the default value.
• [ ] Setting the HTTP section with enabled:true and no endpoint works with the default value.
• [ ] Setting both sections with enabled:true and no endpoint works with the default value.
• [ ] Not setting anything related to OTLP works correctly.