Error list UX/functional issue with LSP pull diagnostics enabled

[mavasani]

#65935 tracks performance issues with LSP pull diagnostics enabled. While working on filing that issue, I also identified a functional/UX issue in the error list.

Repro Steps:

1. Execute the repro steps in LSP pull diagnostics performance issues in squiggles + error list #65935 and notice the changes to the title of the error list from Error List... to Error List, i.e. error list transitioning to steady state.

You can note in the above demo that Error List... very quickly changes to Error List after an edit, even though both the error list and the squiggles have not been updated for the latest snapshot. It takes 10s of additional seconds before the error list and the squiggles get updated. This is due to the underlying performance issue tracked in #65935. However, regardless of the bad performance, the error list title should remain as Error List... until the diagnostics state is not up-to-date, and it seems that is not the case with LSP pull diagnostics enabled. Notice the last demo gif in #65935 for Actual behavior - LSP pull diagnostics disabled + analyzers enabled for current document, and you can see that this is indeed the case with LSP pull diagnostics disabled.

I think that even if we fix the performance issue #65935, we also need to fix the functional/UX issue above and make sure that the user is clearly aware that squiggles and error list are still refreshing.