Added attention requested filter

What does this MR do and why?

Adds an attention requested filter to merge request filters.

Database

https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/8571/commands/30415

https://explain.depesz.com/s/P1rS#html

Migrations

Assignees

Up:

== 20220105111444 AddIndexToMergeRequestAssigneesState: migrating =============
-- transaction_open?()
   -> 0.0000s
-- index_exists?(:merge_request_assignees, :state, {:name=>"index_on_merge_request_assignees_state", :algorithm=>:concurrently})
   -> 0.0044s
-- execute("SET statement_timeout TO 0")
   -> 0.0008s
-- add_index(:merge_request_assignees, :state, {:name=>"index_on_merge_request_assignees_state", :algorithm=>:concurrently})
   -> 0.0154s
-- execute("RESET statement_timeout")
   -> 0.0006s
== 20220105111444 AddIndexToMergeRequestAssigneesState: migrated (0.0290s) ====

Down:

== 20220105111444 AddIndexToMergeRequestAssigneesState: reverting =============
-- transaction_open?()
   -> 0.0000s
-- indexes(:merge_request_assignees)
   -> 0.0040s
-- execute("SET statement_timeout TO 0")
   -> 0.0009s
-- remove_index(:merge_request_assignees, {:algorithm=>:concurrently, :name=>"index_on_merge_request_assignees_state"})
   -> 0.0068s
-- execute("RESET statement_timeout")
   -> 0.0008s
== 20220105111444 AddIndexToMergeRequestAssigneesState: reverted (0.0153s) ====

Reviewers

Up:

== 20220105112014 AddIndexToMergeRequestReviewersState: migrating =============
-- transaction_open?()
   -> 0.0000s
-- index_exists?(:merge_request_reviewers, :state, {:name=>"index_on_merge_request_reviewers_state", :algorithm=>:concurrently})
   -> 0.0028s
-- execute("SET statement_timeout TO 0")
   -> 0.0006s
-- add_index(:merge_request_reviewers, :state, {:name=>"index_on_merge_request_reviewers_state", :algorithm=>:concurrently})
   -> 0.0050s
-- execute("RESET statement_timeout")
   -> 0.0005s
== 20220105112014 AddIndexToMergeRequestReviewersState: migrated (0.0110s) ====

Down:

== 20220105112014 AddIndexToMergeRequestReviewersState: reverting =============
-- transaction_open?()
   -> 0.0000s
-- indexes(:merge_request_reviewers)
   -> 0.0032s
-- execute("SET statement_timeout TO 0")
   -> 0.0007s
-- remove_index(:merge_request_reviewers, {:algorithm=>:concurrently, :name=>"index_on_merge_request_reviewers_state"})
   -> 0.0040s
-- execute("RESET statement_timeout")
   -> 0.0005s
== 20220105112014 AddIndexToMergeRequestReviewersState: reverted (0.0104s) ====

Screenshots or screen recordings

Screen_Recording_2021-11-30_at_15.15.09

How to set up and validate locally

1. Enable mr_attention_requests feature flag.
2. Visit a merge request listing page
3. Click filter bar
4. Use Attention Requested filter

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.

Closes #324854 (closed)