### Godot version

v4.0.beta15.official [4fa6edc88]

### System information

Windows 10

### Issue description

I use a custom keyboard layout (I made it myself), and it has «dead keys» (just like International keyboard layouts have). For example, if I press `'`, nothing happens, but if I press `a` after that, I'll get `á`. If I press `'` and `Space`, I'll get just `'`. And with my layout:
If I press `Shift + .` and then `a`, I will get `ᵄ`.
If I press `Shift + .` and then `Space`, I will get `>`.
If I press `Shift + [` and then `5`, I will get `₅`.
If I press `Shift + [` and then `Space`, I will get `{`.
In beta 14 and before, everything worked fine, but in beta 15 when I press `Shift + .` and `Space`, just nothing happens, I don't get `>`. Same for `Shift + [` and `Space`, I don't get `>`. It seems the problem is with `Shift`, because I still can type `á` (`'` and `a`) or `'` (`'` and `Space`), but not `ä` (`Shift + '` and `a`) or `"` (`Shift + '` and `Space`). In the latter cases I get `á` and `'` as if `Shift` were never pressed.

### Steps to reproduce

Install/add US International keyboard layout or [Extended Latin keyboard layout](https://github.com/godotengine/godot/files/10494466/Layouts.zip) (just run `Extended Latin\ExtLat6\setup.exe`).
Open script editor.
Press `Shift + '`.
Then press `a`.

### Minimal reproduction project

N/A
}
				k->set_keycode(keycode);
				k->set_physical_keycode(physical_keycode);
				k->set_key_label(key_label);
				if (i + 1 < key_event_pos && key_event_buffer[i + 1].uMsg == WM_CHAR) {
					char32_t unicode = key_event_buffer[i + 1].wParam;
					static char32_t prev_wck = 0;
					if ((unicode & 0xfffffc00) == 0xd800) {
						if (prev_wck != 0) {
							ERR_PRINT("invalid utf16 surrogate input");
						}
						prev_wck = unicode;
						break; 
					} else if ((unicode & 0xfffffc00) == 0xdc00) {
						if (prev_wck == 0) {
							ERR_PRINT("invalid utf16 surrogate input");
							break; 
						}
						unicode = (prev_wck << 10UL) + unicode - ((0xd800 << 10UL) + 0xdc00 - 0x10000);
						prev_wck = 0;
					} else {
						prev_wck = 0;
					}
					k->set_unicode(fix_unicode(unicode));
				}
				if (k->get_unicode() && gr_mem) {
					k->set_alt_pressed(false);
					k->set_ctrl_pressed(false);
				}
				k->set_echo((ke.uMsg == WM_KEYDOWN && (ke.lParam & (1 << 30))));