vim: Allow count and repeat for "r" and "shift-r" action (#13287)

Fixing the "r" action just involved adapting `normal_replace` to replace
multiple characters.

Fixing the "shift-r" command was less straightforward. The bindings for
`vim::BeforeNormal` in replace mode were being overwritten and several
other steps required for action repetition were not performed. Finally,
the cursor adjustment after re-entering normal mode was duplicated
(`vim::BeforeNormal` was now triggered correctly) so I removed the
special case for replace mode.

Release Notes:

- Fixed vim "r" action to accept a count argument
- Fixed vim "shift-r" action to accept a count argument and allow
repetition

---------

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

assets/keymaps/vim.json

@@ -645,11 +645,13 @@
       "escape": "vim::NormalBefore",
       "ctrl-c": "vim::NormalBefore",
       "ctrl-[": "vim::NormalBefore",
+      "tab": "vim::Tab",
+      "enter": "vim::Enter",
       "backspace": "vim::UndoReplace"
     }
   },
   {
-    "context": "Editor && VimWaiting",
+    "context": "Editor && vim_mode != replace && VimWaiting",
     "bindings": {
       "tab": "vim::Tab",
       "enter": "vim::Enter",