Add an Apple-period(.) keypress keyboard shortcut

[ph0enix-c0der]

Add an Apple-period(.) keypress keyboard shortcut to the boot / startup launcher, Apple II DeskTop, Disk Copy, the Selector module and all desk accessories. Apple-period(.) should be used to cancel any and all operations and any and all other functions of the Esc key to the extent that Command-period(.) is used in modern macOS in addition to the Esc key.

[inexorabletash]

I've created a Discussion #826 to collect ideas/suggestions around shortcuts. This will generate few notifications than separate issues for each. Feel free to raise this suggestion on that Discussion.