neovim: Add Emmet support

I used Emmet years ago but at some point preferred Pug in Vue. Now that
I use React more, this should make creating tags in JSX easier.

The emmet language server is particularly useful since it becomes
possible to tab complete HTML tags.

home/neovim.nix

@@ -77,6 +77,9 @@ in
 
     # ctags
     universal-ctags
+
+    # emmet
+    emmet-ls
   ];
 
   editorconfig = {
@@ -237,6 +240,7 @@ in
           lspconfig.clangd.setup {}
           lspconfig.texlab.setup {}
           lspconfig.crystalline.setup {}
+          lspconfig.emmet_ls.setup {}
           lspconfig.denols.setup {
             root_dir = lspconfig.util.root_pattern("deno.json", "deno.jsonc"),
           }
@@ -535,6 +539,7 @@ in
       vim-astro
       vim-svelte
       typst-vim
+      emmet-vim
       nvim-treesitter.withAllGrammars
       tagbar
     ];