Description

root_views_ were not cleared in Reset. This could cause root_views_ unnecessarily retained after PlatformViewsController::Reset

Related Issues

Fixes flutter/flutter#69305

Tests

I added the following tests:

testFlutterPlatformViewControllerResetDeallocsPlatformViewWhenRootViewsNotBindedToFlutterView

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Reviewer Checklist

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Breaking Change

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