refactor: extract 'unregisterReceiverSilently' to :common:android

[criticalAY]

Purpose / Description

And one more, -> Removes a dependency on com.ichi2.anki.utils.ext from widget config activities, helping break circular dependencies for feature module extraction

Fixes

• Fixes part of Architecture Discussion: Module Extraction #20737

Approach

See commit

How Has This Been Tested?

Local build

Learning (optional, can help others)

NA

Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[david-allison]

There's also an argument that this extension method could live inside the :widgets module

Implementer's choice. Merge at will

[criticalAY]

I think it can stay in common maybe later if we feel that its actually not the right place then, hitting merge