feat: add highlight provider

[pinbraerts]

Reused code from vim.show_pos. Tried to override vim.api.nvim_echo, but it is extremely unsafe and messed up gui a bit. Then I tried to capture output of the command into buffer but that droped highlights.

I use vim.o.cmdheight = 0 and status bar blinks. Looks like something is blocking gui. Leaving it as draft until I figure out why.

[pinbraerts]

[pinbraerts]

Reduced number of calls to nvim api, but that seems to do nothing. Also I noticed that other bufnr provider (man) cause the same flickering of the status/command line. I'll report that as a different issue.

The provider is ready to squash and merge.

EDIT: cleared some cache files, removed and restored all files in config, updated lazy and suddenly the problem is gone

[pinbraerts]

Also the documentation states that priority is optional, but it is not marked as optional in luadocs, which leads to lua-ls complaining. Is it optional or not? Should I give it some priority? I want it to be the lowest priority by default