Add revoked status to cluster agent tokens

What does this MR do and why?

Adds a status field to cluster agent tokens, which records if the token is active or has been revoked.

Migrations

== 20211209230042 AddStatusToClusterAgentTokens: migrating ====================
-- add_column(:cluster_agent_tokens, :status, :smallint, {:null=>false, :default=>0})
   -> 0.0160s
== 20211209230042 AddStatusToClusterAgentTokens: migrated (0.0161s) ===========

== 20211209230042 AddStatusToClusterAgentTokens: reverting ====================
-- remove_column(:cluster_agent_tokens, :status, :smallint, {:null=>false, :default=>0})
   -> 0.0062s
== 20211209230042 AddStatusToClusterAgentTokens: reverted (0.0211s) ===========

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.

#348386 (closed)