refactor: move CollectionHelper to :anki-common

[david-allison]

• Stacked on feat: no longer implicitly set collection path when DB is used #21343

Purpose / Description

Simple migration commit

Fixes

• Part of Architecture Discussion: Module Extraction #20737

How Has This Been Tested?

Trusting lint & unit tests

Checklist

• 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]

I'll take responsibility for this & merge to keep things moving