feat:(android): Background handling improvements

[CatchABus]

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• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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• Tests for the changes are included - https://github.com/NativeScript/NativeScript/blob/master/tools/notes/WritingUnitTests.md.

What is the current behavior?

There are cases when android native background is not unset when background or background color is set to null.
Also, blank shadow rules seem to cause weird behavior as there can be a view with box-shadow: none by default and that view will have its default drawable removed.

Another thing that was tracked during tests is that cached drawable seems to be broken since ever because it's set to the wrong instance.
This is a continuation of #9615.

What is the new behavior?

This patch takes care of the remaining background handling problems and adds a few android-specific helper functions to get rid of deprecated setColorFilter calls and duplicate code here and there.

[cla-bot]

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[cla-bot]

Thank you for your pull request and welcome to our community. We could not parse the GitHub identity of the following contributors: Dimitris - Rafail Katsampas.
This is most likely caused by a git client misconfiguration; please make sure to:

1. check if your git client is configured with an email to sign commits git config --list | grep email
2. If not, set it up using git config --global user.email [email protected]
3. Make sure that the git commit email is configured in your GitHub account settings, see https://github.com/settings/emails