home: vim: use async path completion

This makes the editor more responsive when completing in directories
that are network mounted or have a large amount of entries.

home/vim/default.nix

@@ -77,6 +77,7 @@ in
       luasnip # Snippet manager compatible with LSP
       friendly-snippets # LSP snippets collection
       nvim-cmp # Completion engine
+      cmp-async-path # More responsive path completion
       cmp-buffer # Words from open buffers
       cmp-nvim-lsp # LSP suggestions
       cmp-nvim-lua # NeoVim lua API