Adds the Android test runtime to makepad_test: builds the APK with
cargo-makepad's standard Java path, installs and launches via adb with
makepad.STUDIO_* intent extras (incl. STUDIO_BUILD), connects the app to an
in-process hub over adb reverse, and waits for startup + responsiveness.
Adds clean in-process hub shutdown (HttpServerHandle + GatewayHandle Drop)
and the STUDIO_BUILD intent parsing on the app side. No native-activity or
NDK APK compilation code is included.
