Improve the touch screen experience

[gkoh]

As of v3.0.0-rc2, all devices are implemented with a text driven menu interface.

For touch screen devices like the M5Core2, this results in:

• smaller than necessary menu entries (which can be difficult to accurately touch)
• waster screen real estate

With the new LVGL graphics library, it should be relatively straightforward to modify most menus to be icon driven.
If icons are laid out in a grid, use of screen can be maximised.

This will require some custom graphics for the icons, the stock symbols provided with LVGL are limited.

[gkoh]

Furthermore, for shutter lock, implement:

• press and slide

This would replace the current 'long-press' shutter lock and could mirror the app (where there is only the shutter button, that can slide).