Add settings overview for digital watchface

[ghost]

What does it do?

Create a settings overlay for the digital watchface to add colourful battery icon and battery percentage display. Implementation is similar to PineTime to avoid adding entries into main settings pages. Closes #582

Screenshots

[kieranc]

I'm very happy to see this implemented, it was on my to-do list!
The settings icon doesn't seem to be quite centered on the screen, is this intentional?
It feels like there are a lot of options which could be implemented but finding space for all the settings could be complicated. BG/text color, seconds display, date format etc. I wonder if the settings buttons which appears on long press could become 2 buttons, leading to 2 pages, one for color settings and one for other options?

[NeroBurner]

works great with InfiniSim

[NeroBurner]

you've changed Settings (i.e. you added new settings). You need to increment settingsVersion

static constexpr uint32_t settingsVersion = 0x0003;

otherwise you are bound to run into the same errors as in PR #1024 (comment)

[ghost]

@NeroBurner thanks for that I've incremented the settings version number
@kieranc no you are right that was an oversight and now corrected

[lman0]

any news @Sykomaniac ?

[ghost]

Happy to update the PR to the latest code base if desired