Align Population Density Data with Commonalities 0.9.0 (r4.4)

[albertoramosmonagas]

What type of PR is this?

Add one of the following kinds:

• correction
• subproject management

What this PR does / why we need it:

Aligns Population Density Data API OpenAPI specification with CAMARA Commonalities 0.9.0 and request/response catalog r4.4:

1. Updated x-camara-commonalities: wip → 0.9.0
2. Migrated deprecated response schemas to new catalog: Generic401 → Unauthenticated401, Generic403 → PermissionDenied403, ...
3. Replaced inline generic examples with $ref to shared examples (INVALID_ARGUMENT, INVALID_CREDENTIAL, INVALID_TOKEN, INVALID_SINK, PRIVATE_KEY_JWT_NOT_CONFIGURED)
4. Replaced inline sink definition with allOf referencing common Sink schema
5. Formatted CAMARA:MANDATORY blocks with blank line after :BEGIN and new additional-error-responses section
6. New Error Responde for 422 POPULATION_DENSITY_DATA.UNSUPPORTED_ASYNC_RESPONSE
7. Corrections and test plan update.

Which issue(s) this PR fixes:

Fixes #N/A

Special notes for reviewers:

• New 422 scenario only triggers when async processing is explicitly requested but unsupported
• Cross-references between sync/async error conditions in Error Handling section ensure consistent behavior documentation

Changelog input

 release-note
Aligned Population Density Data API with CAMARA Commonalities 0.9.0 and request/response catalog r4.4, including new 422 UNSUPPORTED_ASYNC_RESPONSE error and migrated response schemas.

[albertoramosmonagas]

In draft form until the new release automation process begins.

[jgarciahospital]

LGTM