Stopwatch: add persistence

[pptime02]

Stopwatch now keeps running in background if screen is left.
Implemented this by introducing a StopWatchController.
In additon, now an infinite lap count is possible (but only two laps are stored).
Largely based on the work of Louis Pearson (@desttinghim), see #783. Nevertheless, I removed all changes not related to the stopwatch persistence feature.

The corresponding PR to InfiniSim (for adding the StopWatchController) is InfiniTimeOrg/InfiniSim#75.
Would close #303.

[desttinghim]

Cool! Glad to see this is getting completed. I started working on rebasing it but I didn't want to get a build environment set up - thank you for taking it on 🙂

[minacode]

Nice work on this feature. I scrolled through and found some things regarding code style. They are mostly functions starting with a lowercase character. I may not have found all of them.

[desttinghim]

Those are probably leftover from the work I did

[pptime02]

Thank you all for taking a look on it. I think I applied all proposals, and found no further lowercase-functions.

[minacode]

What about those struct types that end with _t? Do they fit our code style?

[pptime02]

What about those struct types that end with _t? Do they fit our code style?

I checked other structs by running rg 'struct .*_t \{' InfiniTime/src/ and rg 'struct .* \{' InfiniTime/src/. Seems like the stopwatch was the only place where _t was used, thus I removed the remaining _t it in the last commit.

[Xylemon]

Any chance of this getting rebased against main? This would be very useful.