Record Slack app permission scopes to allow feature checking logic

What does this MR do and why?

This MR implements the first step required for #374720 (closed) - the storage the set of scopes and the mapping from scopes to features.

Backfilling of existing records is left to the next iteration.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #374720 (closed)