Load Android Gradle Plugin conditionally

[SaeedZhiany]

Summary

This wraps the Android Gradle plugin dependency in the buildscripts section of android/build.gradle in a conditional:

if (project == rootProject) {
    // ... (dependency here)
}

The Android Gradle plugin is only required when opening the project stand-alone, not when it is included as a dependency. By doing this, the project opens correctly in Android Studio, and it can also be consumed as a native module dependency from an application project without affecting the app project (avoiding unnecessary downloads/conflicts/etc).

for more info, you can refer to this thread and especially this comment.

Checklist

• Supports Android
• Supports iOS
• e2e tests added or updated in packages/**/e2e
• Flow types updated
• Typescript types updated

Test Plan

Release Plan

[INTERNAL] [ENHANCEMENT] [ALL MODULES] - Load Android Gradle Plugin only when the android projects of each module opened as a stand-alone project in Android Studio.

[codecov]

Codecov Report

Merging #2860 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2860   +/-   ##
=======================================
  Coverage   88.95%   88.95%           
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  Files         111      111           
  Lines        3436     3436           
=======================================
  Hits         3056     3056           
  Misses        380      380

[CLAassistant]

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