[android_intent_plus] Fix fallback to implicit intent

[vbuberen]

Description

Fix for #245 broke the functionality of safe fallback from explicit to implicit intent when package can't be resolved. This PR adds such functionality back.

Additionally updated Android Gradle plugin and used Gradle version.

Related Issues

Closes #919

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[vbuberen]

I have just moved this check from buildIntent() to be able to set package as null, so the system just opens a chooser.