fix: edge to edge/fullscreen margins

[Chuckytuh]

Platforms affected

Android

Motivation and Context

With the changes added on #1817, when the app is in edge to edge mode or fullscreen, the left and right margin values are being read directly from the insets thus causing the webview to not take the full width/height in fullscreen or not be overlaid by navigation/gesture bar when rotation the device.

It's unclear to me whether this was intentional but, if it wasn't, this is an attempt to fix it to what I'd expect is the correct behavior.

Description

Testing

Created a dummy application and manually ran it on Android 10 and 16 and compared the results visually.

Current behavior:

	non-e2e	e2e	fullscreen
Android 16
Android 10

Behavior after the fix on this PR:

	non-e2e	e2e	fullscreen
Android 16
Android 10

Thanks Kepa for the help!

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.79%. Comparing base (5bca218) to head (7faa0c4).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1847   +/-   ##
=======================================
  Coverage   60.79%   60.79%           
=======================================
  Files          23       23           
  Lines        4811     4811           
=======================================
  Hits         2925     2925           
  Misses       1886     1886           

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[erisu]

It's unclear to me whether this was intentional but, if it wasn't, this is an attempt to fix it to what I'd expect is the correct behavior.

I do not remember why left and right was not handled, but I believe the behavior of the PR is correct and preferred.

The code changes looks good to me. I also tested with emulator SDK 36, 35, 30, and 24.