Real time todos in issuable sidebar

Problem

We've added the ability to mark/unmark todos on a collapsed sidebar.

It would be great to take this even further and real time todos in the sidebar. When I comment on an issue that marks a todo as complete, the sidebar should update to reflect that I no longer have a todo.

Scope

• Make todos in issuable sidebar and collapsed sidebar reflect the real status of the object making it a SSOT even across browser tabs