fix(paste): improve repeating of pasted text (#30438)

- Fixes 'autoindent' being applied during redo.
- Makes redoing a large paste significantly faster.
- Stores pasted text in the register being recorded.

Fix #28561

src/nvim/edit.c

@@ -907,6 +907,10 @@ static int insert_handle_key(InsertState *s)
   case K_IGNORE:      // Something mapped to nothing
     break;
 
+  case K_PASTE_START:
+    paste_repeat(1);
+    goto check_pum;
+
   case K_EVENT:       // some event
     state_handle_k_event();
     // If CTRL-G U was used apply it to the next typed key.