[Cleanup]: Add Tests to the code (`@NeedsTest`)

[!NOTE] This issue does not need to be assigned to you before you work on it

A number of paths of the code have been identified as requiring automated testing.

Typically this is regression testing: if a bug has been found, then it's useful to have a unit test which would have failed due to the bug.

1. Find a usage of @NeedsTest: https://github.com/ankidroid/Anki-Android/blob/main/AnkiDroid/src/main/java/com/ichi2/annotations/NeedsTest.kt a. Ensure that the method(s) you are testing are in use.
2. Post the test(s) that you're handling on this issue, so people don't duplicate work
3. Write a unit test (/test, not /androidTest)
4. Ensure that re-introducing the bug or issue would break the test
5. Submit a Pull Request