Add an Android test to avoid regressions

The following reviews fixed some lint issues on Android:
https://codereview.qt-project.org/249990
https://codereview.qt-project.org/249484
https://codereview.qt-project.org/250690
https://codereview.qt-project.org/251191
https://codereview.qt-project.org/249658

There are 2 builds in the Qt CI building Qt for Android on Linux RHEL_7_4. But they are using the configuration option "-nomake examples". I do not see any job that try to build a full apk. We should add a job, using the templates from qtbase/src/android/templates and treat lint warnings as errors.