backend using io.KeyMap[], io.KeysDown[] should call io.AddKeyEvent() instaed

[kiraYuukiAsuna]

[Problem]
According to imgui release v1.87 :
2022/02/29: We discovered a backward-compatibility regression in 18700:
Direct legacy reads from io.KeysDown[] won't work with new backends.
And in particular io.KeysDown[GetKeyIndex[XXX]) will buffer overflow in old and new backends.
You can refer to https://github.com/ocornut/imgui/issues/4921
[Solution]
Backend writing to io.KeyMap[], io.KeysDown[] -> backend should call io.AddKeyEvent()