Allow optional copyable text in setup flows

[afeldman1]

What does this implement/fix?

Allows a field to be copyable in a setup flow. This is for convenience of copying setup codes.

related issue :

music-assistant/frontend#2710
music-assistant/server#6268

Types of changes

• Bugfix (non-breaking change which fixes an issue) — bugfix
• New feature (non-breaking change which adds functionality) — new-feature
• Enhancement to an existing feature — enhancement
• Breaking change (fix or feature that would cause existing functionality to not work as expected) — breaking-change
• Refactor (no behaviour change) — refactor
• Documentation only — documentation
• Maintenance / chore — maintenance
• CI / workflow change — ci
• Dependencies bump — dependencies

Checklist

• The code change is tested and works locally.
• pre-commit run --all-files passes.
• pytest passes, and tests have been added/updated under tests/ where applicable.
• Any consumer of a changed model is updated, and the companion PR in music-assistant/server is linked.
• I have read and complied with the project's AI Policy for any AI-assisted contributions.

[marcelveldt]

makes sense, thanks @afeldman1 !