Add screen lock mechanism for touch screens

[gkoh]

          > One other thing that might be worth investigating with the Core2 is some way to disable the touchscreen using the physical buttons. I know there's times when I'm out on location where I drop the remote in a pocket, so preventing erroneous touches would be useful

Oh, like a 'lock' button. I'll create a new issue to track this.

Originally posted by @gkoh in #150 (comment)

[gkoh]

This looks ... tricky.
The M5Core2 has 2 physical buttons which appeared hard-wired to power and reset.
Whilst we can kinda read them, there's a risk of accidental power off or reset instead 😐

Ugh, might need to learn from the smart phones: slide to lock/unlock

[gkoh]

This looks ... tricky. The M5Core2 has 2 physical buttons which appeared hard-wired to power and reset. Whilst we can kinda read them, there's a risk of accidental power off or reset instead 😐

Ugh, might need to learn from the smart phones: slide to lock/unlock

Actually, this is much simpler than I thought, the underlying M5 library can detect and distinguish double clicks on the power button (without removing power).