### Godot version

4.0 beta 15

### System information

Windows 10

### Issue description

It happened with both Google IME and MS-IME, and there was no problem until Beta14.
When typing Japanese characters, it is common to select a character from the suggestion window and then start typing the next character before confirming.
In this case, uncommitted characters are forcibly committed, and input of the next character begins.

**↓Beta15**

https://user-images.githubusercontent.com/186786/214753450-b493cca6-2644-4b3d-8cd2-660565cc3547.mp4

**↓Beta14**

https://user-images.githubusercontent.com/186786/214755127-dde819cc-4d63-403a-99b0-09821671f74e.mp4



### Steps to reproduce

It happened with both Google IME and MS-IME in beta15

### Minimal reproduction project

It is project independent and happens in the editor.
_THREAD_SAFE_METHOD_
	DisplayServer::WindowID window_id = _get_focused_window_or_popup();
	const WindowData &wd = windows[window_id];
	if (!wd.ime_active) {
		return Vector2i();
	}
	int cursor = ImmGetCompositionStringW(wd.im_himc, GCS_CURSORPOS, nullptr, 0);
	int32_t length = ImmGetCompositionStringW(wd.im_himc, GCS_COMPSTR, nullptr, 0);
	wchar_t *string = reinterpret_cast<wchar_t *>(memalloc(length));
	ImmGetCompositionStringW(wd.im_himc, GCS_COMPSTR, string, length);
	int32_t utf32_cursor = 0;
	for (int32_t i = 0; i < length / sizeof(wchar_t); i++) {
		if ((string[i] & 0xfffffc00) == 0xd800) {
			i++;
		}
		if (i < cursor) {
			utf32_cursor++;
		} else {
			break;
		}
	}
	memdelete(string);
	return Vector2i(utf32_cursor, 0);
}
String DisplayServerWindows::ime_get_text() const {