R1:020f3c729a0a

Fix username typeahead in Remarkup with German keyboard layout

Summary:
Ref T10252. The previous fix rPa8a9fddb0738 only works for macOS.
Under Windows the @ symbol is composed of AltGr+q. For Chrome and Edge the "AltGr" keypressEvent is like pressing the Control key and the Alt key at the same time.
This fix changes the condition in such a way, that this case (pressing Control and Alt at the same time) is not blocked.

Test Plan:
Testing for the issue:

- Launch Windows 10, Select German Keyboard, Use…