Keep lint panel open until dismissed by user

[CarolineDenis]

from @combs-a :

Currently, the behavior of the summary is that it disappears after you start editing, and you can't bring it back up unless a) you have errors and click save, or b) know the shortcut.

In my opinion, this is a bit flawed, since if you edit it you can no longer see the list of warnings unless you know the shortcut--which isn't told to the user in the editor itself. This will lead to the QoL issue of having to scroll to find the warnings again, or having to find it in documentation elsewhere.

A better behavior would be to keep it up until it is dismissed, since it's a bit clearer to users, and doesn't mean you have to click save or know the hotkey for it. Alternatively, having a tooltip in the XML editor itself that lets you know that you can bring it back up with Ctrl+Shift+M would be fine.

Example of the behavior:

3_errorsummary.mp4