Detect model scope changes as database changes in Danger

What does this MR do and why?

Detects model scope changes as database changes for Danger.

Recently, we noticed that some merge requests that change database queries are not being identified for database review, when the changes are to scopes inside of models (example MR).

This can risk production incidents if poorly performing queries are introduced accidentally, so identifying these changes is an important way to mitigate risk.

Relates to #419001 (closed)

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 #419001 (closed)