#651 test source set resources

[ExNDY]

Depends on #895

#651 — Generate resources for test source sets

Closes #651.

Fixed

• Attach generated Kotlin sources directly to every Kotlin Multiplatform source
  set, including shared test source sets such as commonTest and iosTest.
• Generate resource objects for platform test source sets such as jsTest and
  iosTest when they contain their own moko-resources directory.
• Keep test resources isolated from resources of the parallel main hierarchy
  when both are linked into the same test binary:
  • generated resource object names include the test source-set name;
  • JVM and JS string/plural bundle files include the same namespace suffix;
  • Apple test resources use their own PlatformDetailsProvider, preventing
    main-resource lookups from being redirected to the test bundle.
• Resolve Android test resources through the namespace of the corresponding
  test component instead of the main component's R class.

Compatibility

Production resource APIs are unchanged. When a test hierarchy and its parallel
main hierarchy both contain resources, test-only resources are exposed through
a source-set-qualified object such as SharedRescommonTest. This follows the
existing naming rule for resource objects generated below the main source set
and avoids duplicate declarations and runtime resource shadowing.

Verification

• The Kotlin 2 sample exercises test-only strings, plurals, colors, images,
  files, and assets from commonTest, plus resources declared in jsTest and
  iosTest.
• A source set named sharedChecks, shared by the JVM and JS test
  compilations, verifies that test/main association does not rely on source-set
  naming conventions.
• Generator tests verify isolated JVM/JS string and plural bundle names.
• Generator tests verify that Apple strings, plurals, colors, images, fonts,
  files, and assets all reference the isolated test PlatformDetailsProvider.