Fixes #42444

• Changed accepts_text_input on the editor to be more precise. Previously, it returned true only in insert mode. Now it also returns true when an operator is pending.
• On Windows, we disable the IME whenever there is no input handler which accepts_text_input.
  • How this improves Vim mode: in insert mode, the IME is enabled; in normal mode, it is disabled (command keys are not intercepted); when an operator is pending, the IME is re-enabled.

Release Notes:

• On Windows, the IME is disabled in Vim normal and visual modes.