Draft: Annotate queries with feature_category

What does this MR do?

This adds feature_category:? annotations to Marginalia query comments, if available from context (web/sidekiq).

An example looks like so, notice the additional feature_category:authentication_and_authorization component:

/*application:action_cable,correlation_id:01F8VWT3T46GG5QEG41DEPTBYF,endpoint_id:SessionsController#new,feature_category:authentication_and_authorization*/ 
SELECT "broadcast_messages".*
FROM "broadcast_messages" 
WHERE (ends_at > '2021-06-23 07:37:05.492645')
  AND "broadcast_messages"."broadcast_type" = 1
ORDER BY "broadcast_messages"."id" ASC

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.