Audit implementation of all controllers against "Guidelines for Writing Controllers"

[desi]

Motivation

Some of our controllers currently do not fulfill their intended specifications correctly, which may affect downstream clients where the controllers are used.

To understand the extent of the problem and its impact, we should perform an audit on all controllers, evaluating whether their implementation of the BaseController API is both complete and correct, and documenting any points for improvement. Tickets should be created for any fix suggestions and communicated to the appropriate codeowners.

We now have documentation that we can reference as a source of truth during this process.

Acceptance Criteria

• Tickets are created for auditing each controller.
• All controllers are audited and reports left in the corresponding tickets (a simple "all-clear" should do if no problems are found).
• Tickets are created for fixing all issues documented in the reports, and these are assigned to the appropriate codeowners.

References

• See Fix controllers with missing or incorrect messenger-related types #4579 for a similar effort with more limited scope.

[desi]

@MajorLift please fill in details here.