[Android] Add test case for loadAppFromManifest().

This patch contains the test case about loadAppFromManifest on
embedded and shared mode.
Invoke loadAppFromManifest on main thread, then get the title
and compare the two titles.

For embedded client test:
1. install XWalkRuntimeClientEmbeddedShell.apk
2. python build/android/test_runner.py instrumentation \
--test-apk=XWalkRuntimeClientEmbeddedTest -v -f \
testLoadAppFromManifest

For shared client test:
1. install XWalkRuntimeLib.apk
2. install XWalkRuntimeClientShell.apk
3. python build/android/test_runner.py instrumentation \
--test-apk=XWalkRuntimeClientTest -v -f testLoadAppFromManifest