[xwalkdriver] Add tests.xml for xwalkdriver tests

- Add tests.xml for testskit-lite
- Improve Android test steps
- Pack APK zip
Here only have test set but without test case. Please check below tests.xml; testkit is able to run python script directly.

```
crosswalk-project/crosswalk-test-suite$ grep 'python' -r */*/tests.xml
misc/wrt-usecase-android-tests/tests.xml: and  package the extension with argument like: python make_apk.py --name=Example --package=org.xwalk.example --app-root=test_data/entry --app-local-path=contactextension.html --extensions=test_data//extensions/contactextension/ --mode=embedded
wrt/wrt-extension-android-tests/tests.xml: and  package the extension with argument like: python make_apk.py --name=Example --package=org.xwalk.example --app-root=test_data/entry --app-local-path=contactextension.html --extensions=test_data//extensions/contactextension/ --mode=embedded
wrt/wrt-manifest-android-tests/tests.xml:          <test_script_entry test_script_expected_result="0" timeout="100000" >python $HOME/tct/opt/wrt-manifest-android-tests/test.py
wrt/wrt-manifest-tizen-tests/tests.xml:          <test_script_entry test_script_expected_result="0" timeout="100000" >python test.py
wrt/wrt-packertoolauto-android-tests/tests.xml:          <test_script_entry test_script_expected_result="0" timeout="100000" >python $HOME/tct/opt/wrt-packertoolauto-android-tests/test.py
```