Add customized diff for unique_writer_identity on resource google_logging_project_sink

[modular-magician]

For logging_project_sink we are adding a customized diff for unique_writer_identity. If big_query_options is populated this field must be true.

Closes 6122

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Release Note Template for Downstream PRs (will be copied)

logging: added plan time validation for `unique_writer_identity` on `google_logging_project_sink`

Derived from GoogleCloudPlatform/magic-modules#4301