Controlling Background Migrations via ChatOps - Iteration 2

As a follow up iteration for the issue: #346357 (closed)

We should add the ability for Gitlab Engineers to control the Batched Background Migrations via ChapOps commands.

When developers get the ID of a Background Migration via the command: /chatops run background-migration list --database DATABASE --env ENV they should be able to issue any of the commands:

• /chatops run batched-background-migration pause --database DATABASE --env ENV ID
• /chatops run batched-background-migration resume --database DATABASE --env ENV ID