Improve 'mini.notify' to reduce LSP progress flicker

[echasnovski]

Thanks for sharing and the feedback! I don't really work with Rust, but when testing it does look too flickery.

Couple of thoughts:

• Making notifications sorted based on ts_add time is not complicated to do manually, which you have. I do wonder if it indeed might be a good idea to have it by default. Probably would require extra MiniNotifyDone highlight group to dim already finished tasks to easier differentiate from active ones.
• I agree that not wrapping by default should be easier. I'll take a look, but adding config.window.wrap looks reasonable.
• Throttling LSP progress updates by default might also be a good idea. I'll also take a look.

I had an idea of revisiting 'mini.notify' to see if it can be naturally extended to show spinners and account for the new Progress event on Nightly, so this will be a good time to revisit all of these. Not sure about the time frame, though.

Originally posted by @echasnovski in #36 (reply in thread)