test: add end-to-end demo smoke test

[kikoso]

Summary

Adds an end-to-end smoke test for the demo app, the same approach as googlemaps/android-maps-utils#1805.

• DemoSmokeTest (parameterized, one case per demo): starts MainActivity, opens the demo through the menu, waits for its map, zooms out and back in, checks the demo is still in the foreground, and navigates back. StreetViewActivity has no map and is only checked for staying open.
• DemoCatalogTest: fails if a demo activity is declared in the manifest but missing from the menu (or the other way round), so new demos added to allActivityGroups are covered automatically.
• The only app change is test tags on the menu cards in Demo.kt.

No new workflow: the existing emulator job (createDebugCoverageReport) runs all of maps-app/src/androidTest, so it picks the tests up. Changes to that job:

• Passes requireMapLoaded=true when ACTIONS_API_KEY is available, so the smoke test also waits for map tiles to render. Without the secret (forks, Dependabot) the smoke test still runs, it just does not wait for tiles.
• Runs on API 36 (x86_64) instead of API 29. Emulators never update Google Play services, and in android-maps-utils#1805 the bundled version on older images crashed inside Play services when adding advanced markers. API 36 bundles 25.26, which works. This also moves the existing instrumentation tests to API 36.

Notes

• Unlike utils, this does not enable Android Test Orchestrator, because the same job collects instrumentation coverage and clearing package data between tests risks losing the coverage files. A crashing demo therefore aborts the rest of the run, though the failure is still reported.
• The GoogleMap composable registers its loaded callback once, so when waiting for tiles the test replaces it and a demo's own onMapLoaded stops firing for the rest of that case. Demos only use it for UI like loading indicators, which the test does not check.

Testing

On a local API 34 emulator:

• DemoCatalogTest 1/1 and DemoSmokeTest 22/22 pass without the map-loaded check (about 1:45).
• Same with requireMapLoaded=true and a real key: 23/23 (about 2:15), including lite mode.
• :maps-app:lintDebug passes.

Run locally with:

./gradlew :maps-app:connectedDebugAndroidTest \
  -Pandroid.testInstrumentationRunnerArguments.package=com.google.maps.android.compose.smoke

[github-actions]

Coverage (unit tests)

No unit baseline recorded in coverage/history.csv yet, so this run only reports absolute numbers.

Module	Line %	Change	Branch %	Change
maps-compose	0.00%	new	0.00%	new
maps-compose-utils	2.04%	new	0.49%	new
maps-compose-widgets	0.00%	new	0.00%	new
TOTAL	0.42%	new	0.09%	new

_{Line and branch coverage from unit test reports. History is recorded in coverage/history.csv after each merge to main.}

[kikoso]

Closing as a duplicate of #1007. The CI changes from here (API 36, Ubuntu with KVM, and requireMapLoaded when the key secret is available) and the zoom check have moved there.