remove android gradle plugin

[dulmandakh]

Summary:

RN modules don't need to include Android Gradle Plugin because it's included in App project, and version its mismatch between app and module causes issues.

This PR removes Android Gradle Plugin from android or module project, and created a root project, creating build.gradle.kts file, so that we can develop with Android Studio. Also removed buildToolsVersion because it's no longer required by Android Gradle Plugin. Then changed minSdkVersion to be 16 to comply with RN.

Once this PR merged, developers need to open async-storage in Android Studio instead of android folder inside it.

Test Plan:

The module will work as usual and expected

[dulmandakh]

@krizzu please review and merge

[krizzu]

@dulmandakh Thank you for the contribution! This looks great, left a question and small comment for you.

[dulmandakh]

@krizzu fixed, please merge

[friederbluemle]

Hi @dulmandakh - What kind of issues were you seeing when there is a mismatch of the the app project and a module? Can you please link me to an example?

[krizzu]

@dulmandakh Actually, I think we don't need to have gradle project in the root. When developing AsyncStorage, you'd normally do it by using Android App - which we have, in example directory and it's already using AsyncStorage module as subproject.

Can you checkout changes with build.gradle.kts and executables please?

[dulmandakh]

@krizzu removed Gradle wrapper

[friederbluemle]

@krizzu @dulmandakh - Please check a slightly different approach here: #209 - It achieves the same result (avoiding unnecessary dependency downloads/conflicts in an app project), but keeps the buildscript dependency in place. With this it is still possible to open the android folder in Android Studio, and build this library stand-alone.

[krizzu]

Closing in favor of #209