vim: Implement named registers (#12895)

Release Notes:

- vim: Add support for register selection `"a`-`"z`, `"0`-`"9`, `"-`.
`"_` and `"%`
([#11511](https://github.com/zed-industries/zed/issues/11511))

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

docs/src/vim.md

@@ -215,9 +215,9 @@ Some vim settings are available to modify the default vim behavior:
 ```json
 {
   "vim": {
-    // "always": use system clipboard
-    // "never": don't use system clipboard
-    // "on_yank": use system clipboard for yank operations
+    // "always": use system clipboard when no register is specified
+    // "never": don't use system clipboard unless "+ or "* is specified
+    // "on_yank": use system clipboard for yank operations when no register is specified
     "use_system_clipboard": "always",
     // Lets `f` and `t` motions extend across multiple lines
     "use_multiline_find": true