fix: fix the nightmode not working problems (#1633)

fix: fix the problem that nightmode switch stops working

chore: properly update the keyboard ascii status.

There is a bug when current keyboard is number/symbol etc. When trying to switch to chinese keyboard, current behaviour will not update ascii status.
Removed currentAsciiMode as it seems like not used after the change.

Also allow keyboard to switch to last locked keyboard when there is no ascii keyboard assigned (numbers, symbols etc.)