* feat(theme): add separate diagnostic colors
This commit adds separate diagnostic highlight colors for the different
types of LSP severities. If the severity type doesn't exist or is
unknown, we use some fallback coloring which was in use before this
commit.
Some initial color options were also added in the theme.toml
Resolves issue #2157
* feat(theme): add docs for new diagnostic options
* feat(theme): adjust defaults & reduce redundancy
- the different colors for different diagnostic severities are now
disabled in the default theme, instead diagnostics are just generally
underlined (as prior to the changes of this feature)
- the theme querying is now done once instead of every iteration in the
loop of processing every diagnostic message
- Rename markup.underline.link to markup.link.url
- Add markup.link.label
- Add markup.quote
(The constructor theme scope was missing from the
docs, so unrelated to this commit).
I like it, but it clashes with diagnostics underlines since we can't
color them differently in the terminal. If undercurl support is
sufficient enough I'd consider changing diagnostics to use that instead.
* Add default color for cursor match
Not all terminals support dim, for those terminal that does not support
this (konsole, item2, wezterm), users cannot differentiate between match
and primary cursor. So set a color for this.
* Use alacritty dim color for match
Adds `ui.linenr.selected` which controls highlight of linu numbes which
have cursors on.
- Fallback to linenr if linenr.selected is missing
- Update docs and themes
- Add TODOs for themes with temporary linenr.selected
