[xwalkdriver] Add tests.xml for xwalkdriver tests

- Add tests.xml for testskit-lite
- Improve Android test steps
- Pack APK zip
From @liuct:

> For the tests.xml provided to webdriver test. You need to specify "type" attribute for each test set Node.
Otherwise it will get error: invalid test set type.
type="ref" or type="js" or type="script"