Re-lands https://github.com/zed-industries/zed/pull/24446 with a more
appropriate fix


https://github.com/user-attachments/assets/45f665f0-473a-49bd-b013-b9d1bdb902bd

After activating 2nd diagnostics group, `find_map` code for next
diagnostics did not skip the previous group for the same place.

This time, instead of fiddling with the diagnostics group comparison,
the code splits the diagnostics by search place, looks up the active
group (if any) in both split parts, and selects the entries after the
group elements.

Release Notes:

- Fixed `editor::GoToDiagnostics` action stuck when multiple diagnostics
groups belong to the same place