Issue inline editing

What does this MR do?

Moves the issue edit form for title & description inline. The other dropdown's (labels, milestones etc.) are already in the sidebar so they are not present in this inline form.

The user clicks the edit button in either desktop or mobile view & can then update the title, description, confidential status or move the issue to another project without having to navigate away from the page they are currently on.

If new data from the realtime endpoint is received after the title or description has been edited then a warning message is displaying asking the user to check the changes before saving. This warning box also contains a link to the issue that opens in a new window (follows the same behaviour as the current edit form).

Screenshots (if relevant)

What are the relevant issue numbers?

Closes #24873 (closed)