home: vim: add 'lsp_lines'

I dislike the diagnostics *next* to affected lines.

This looks neater, though the best look would be a simple hover window
or status line message instead, like ALE used to do.

It might grow on me however.

home/vim/default.nix

@@ -64,6 +64,7 @@ in
 
       # LSP and linting
       lightline-lsp
+      lsp_lines-nvim # Show diagnostics *over* regions
       null-ls-nvim # LSP integration for linters and formatters
       plenary-nvim # 'null-ls' dependency
     ];