[Android] Add the test case about enableRemoteDebugging.

This patch contains the test case about enableRemoteDebugging on
embedded and shared mode.
Enable the enableRemoteDebugging by the broadcast. From the
output of 'cat /proc/net/unix' command, find the abstract socket
name opened for remote debugging.

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

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 testEnableRemoteDebugging