Something I think would be nice to have in eglot is some kind of
progress indicator for long running requests. Attached is my attempt at
implementing these. The patch contains links to relevant LSP specs in
the commit message.

Here is a link to an old github discussion about progress notifications:
https://github.com/joaotavora/eglot/discussions/835 

It uses the built in progress-reporter to display progress in the
echo area. Something that may be missing is a way for the user to
enable/disable this. Not sure what the right facilities are for that.
The eglot-stay-out-of pattern maybe? I didn't include that because I'm
not sure what to "stay out of". Maybe the symbol `progress-reporter'?
Happy to add something like that.