test: add a smoke test that opens every ApiDemos demo

[kikoso]

Adds an end-to-end smoke test for ApiDemos, matching the ones in android-maps-utils (#1805) and android-maps-compose (#1007).

For every demo activity in java-app and kotlin-app (read from the manifest, so new demos are picked up with no test change), the test:

• launches it and checks it reaches RESUMED,
• waits for its map or Street View panorama (MapView, StreetViewPanoramaView, SupportMapFragment or SupportStreetViewPanoramaFragment) to be laid out and ready,
• zooms the map out and back in, waiting for tiles when requireMapLoaded=true,
• recreates the activity and checks it again,
• fails on any uncaught exception.

Demos that need a map ID (advanced markers and the two data-driven styling demos) are skipped when none is configured.

Bugs it found (fixed here)

• BackgroundColorCustomizationProgrammaticDemoActivity (Kotlin) cast the map type switch to CheckBox, so it crashed on rotation. It also only called getMapAsync after a recreate, so on first launch the toggle did nothing. Now matches the Java version.
• LayersDemoActivity (Kotlin) crashed on rotation: the spinner calls onItemSelected with a null view, and the override declared it non-null. Same signature fixed in CircleDemoActivity and PolylineDemoActivity.

CI

• New demo-smoke-test.yml runs both apps on an API 36 emulator (Ubuntu with KVM). Older images bundle a Play services version where advanced markers crash.
• instrumentation-test.yml excludes the smoke package.
• Both apps now use the Android Test Orchestrator, so one crashing demo does not abort the rest of the run.

Like the existing instrumentation workflow, this needs the ACTIONS_API_KEY secret, which this repo does not have yet, so the job is skipped until an admin adds it.

Local results (API 34 emulator, real key)

• kotlin-app: 86 tests, all pass except 6 skipped for the map ID. One result (demoLaunchesAndShowsMap[PolylineDemoActivity]) was missing from the full run's report and passed when rerun alone.
• java-app: 86 tests, all pass except 6 skipped for the map ID.

The Gradle report lists skipped tests as failures, but the build passes.

A follow-up will add a menu navigation test once the catalog stack (#2422 to #2428) lands.

BEGIN_COMMIT_OVERRIDE
fix: crash on rotation in Kotlin BackgroundColorCustomizationProgrammaticDemoActivity
fix: crash on rotation in Kotlin LayersDemoActivity
test: add a smoke test that opens every ApiDemos demo
END_COMMIT_OVERRIDE