prioritize gutter diagnostics

[sbromberger]

Describe your feature request

Right now if there are multiple issues of different severity on a given line, it is possible that a less-severe (i.e., warning) gutter icon overrides a more severe (i.e., error) icon. It would be nice if the highest-severity issue could be displayed. Here's an example:

On line 11, there are two errors and one warning (the suggestion to borrow). The gutter icon briefly flashed a red dot, but then the yellow dot overwrote the red dot. It'd be better if the red dot persisted because that is probably something that should take a higher precedence.

[the-mikedavis]

I agree these should be prioritized by severity 👍

The relevant source for this is in helix_view::gutter::diagnostic if you'd like to give it a try