FNX-14444 ⁃ For #13262: Update gradle

[NotWoods]

No description provided.

[codecov-commenter]

Codecov Report

Merging #13263 into master will increase coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master   #13263      +/-   ##
============================================
+ Coverage     28.35%   28.40%   +0.04%     
- Complexity     1033     1042       +9     
============================================
  Files           418      418              
  Lines         16826    16895      +69     
  Branches       2190     2189       -1     
============================================
+ Hits           4771     4799      +28     
- Misses        11710    11751      +41     
  Partials        345      345              

Impacted Files	Coverage Δ	Complexity Δ
...illa/fenix/migration/MigrationTelemetryListener.kt	75.00% <0.00%> (-25.00%)	2.00% <0.00%> (ø%)
...zilla/fenix/session/NotificationSessionObserver.kt	75.00% <0.00%> (-10.72%)	2.00% <0.00%> (ø%)
...ain/java/org/mozilla/fenix/perf/StartupTimeline.kt	55.55% <0.00%> (-6.95%)	2.00% <0.00%> (ø%)
...org/mozilla/fenix/home/tips/ButtonTipViewHolder.kt	86.20% <0.00%> (-6.39%)	4.00% <0.00%> (ø%)
...g/mozilla/fenix/settings/DropDownListPreference.kt	33.33% <0.00%> (-4.17%)	0.00% <0.00%> (ø%)
...deletebrowsingdata/DeleteBrowsingDataController.kt	75.00% <0.00%> (-3.95%)	0.00% <0.00%> (ø%)
...org/mozilla/fenix/push/WebPushEngineIntegration.kt	95.12% <0.00%> (-2.38%)	5.00% <0.00%> (ø%)
...ava/org/mozilla/fenix/tabtray/TabTrayViewHolder.kt	62.33% <0.00%> (-1.67%)	11.00% <0.00%> (ø%)
...in/java/org/mozilla/fenix/sync/SyncedTabsLayout.kt	29.26% <0.00%> (-1.51%)	0.00% <0.00%> (ø%)
.../logins/controller/SavedLoginsStorageController.kt	57.14% <0.00%> (-0.59%)	8.00% <0.00%> (ø%)
... and 36 more

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[pocmo]

I'm all for updating this. 👍

The Android Gradle plugin site has a list of plugin versions and the required Gradle version:
https://developer.android.com/studio/releases/gradle-plugin

We are currently using version 3.5.0 of the plugin. Version 6.5.1 of Gradle seems way ahead. I wonder if we should try to update to a 4.x version of the plugin at the same time (which at least recommends a 6.x+ Gradle version).

But having everything pass on tasklcluster here is already a good sign that things are not terribly broken. :)

[NotWoods]

Android Gradle Plugin 3.3 and up is compatible with Gradle 6.5. I'll work on AGP updates too but that requires additional work as the breaking changes aren't well documented.