feat: add persistance to stopwatch

[hank-milliken]

I am trying to achieve this: https://github.com/InfiniTimeOrg/InfiniTime/discussions/2288

DISCLAIMER: I have no idea how C++ works. This is pure trial & error craziness.

This is basically copy-cat of the https://github.com/InfiniTimeOrg/InfiniTime/pull/2141 only applied on top of current main.

:point_right: To run this in the InfiniSim, this PR is needed: https://github.com/InfiniTimeOrg/InfiniSim/pull/163

• [x] Only implemented for WatchFaceDigital

[github-actions[bot]]

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