Move the testapp GameLoops logic to an androidlib

[a-maurice]

Description

Unity is supposed to merge AndroidManifest files, but starting in 2020 it only checked in androidlib folders. We had incorrectly moved the AndroidManifest for GameLoops up to Plugins/Android, but that prevents it from merging in other files, like the Messaging logic. So move the GameLoops back into a subfolder, but named correctly to work with newer versions of Unity.

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Testing

Messaging with 2019: https://github.com/firebase/firebase-unity-sdk/actions/runs/2633267403
Messaging with 2020: https://github.com/firebase/firebase-unity-sdk/actions/runs/2633268832
All with 2019: https://github.com/firebase/firebase-unity-sdk/actions/runs/2637673488
(The Firestore issue is an ongoing unrelated problem)

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Type of Change

Place an x the applicable box:

• Bug fix. Add the issue # below if applicable.
• New feature. A non-breaking change which adds functionality.
• Other, such as a build process or documentation change.

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[sunmou99]

LGTM

[github-actions]

❌  Integration test FAILED

Requested by @firebase-workflow-trigger[bot] on commit 230b8a6
Last updated: Fri Jul 8 21:00 PDT 2022
View integration test log & download artifacts

Failures	Configs
analytics	[TEST] [ERROR] [2019] [macos] [1/5 Platform(s): iOS] [1/3 Test Device(s): simulator_target]
firestore	[BUILD] [ERROR] [2019] [macos] [1/3 Platform(s): Android]
functions	[TEST] [ERROR] [2019] [macos] [1/5 Platform(s): iOS] [1/3 Test Device(s): simulator_target]
installations	[TEST] [ERROR] [2019] [macos] [1/5 Platform(s): iOS] [1/3 Test Device(s): simulator_target]
messaging	[TEST] [ERROR] [2019] [macos] [1/5 Platform(s): iOS] [1/3 Test Device(s): ios_target] [TEST] [FAILURE] [2019] [macos] [1/5 Platform(s): iOS] [1/3 Test Device(s): simulator_target]
storage	[TEST] [FAILURE] [2019] [macos] [3/5 Platform(s): windows iOS ubuntu] [1/3 Test Device(s): simulator_target]