Recognize `Escape` key when not used in escape sequence

[Jojo4GH]

Moved from comment on pull request: https://github.com/ajalt/mordant/pull/192#issuecomment-2254610167

ESC can both mean the escape key was pressed as well as be the start of an escape sequence. It might be possible to also use a short timeout on the second read here. Since every ESC in escape sequences is quickly followed by other characters this would allow to distinguishing from single Escape key presses and users would not need to press escape twice.