refactor: extract isSdCardMounted from AnkiDroidApp to :common:android

[criticalAY]

Purpose / Description

Moving a step closer to extracting widget and finally feature to module, the PR extract isSdCardMounted to :common:android

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]

LGTM. I'd prefer it if this were also refactored to an SdCard object in a second commit

Implementers choice, merge at will

[criticalAY]

Sure! I will make the change here itself

[david-allison]

Maybe something useful here in terms of ideas: https://github.com/david-allison/Anki-Android/commits/sdcard/

EDIT: There's SdCard.isMounted in commit 1