Remove all uses of sprintf (#958)

Remove all uses of sprintf (#958)

Deprecate sprintf in favor of snprintf or QString::asprintf... This buys time until we have {fmt}

* remove unused bgr in tpo.cc
* more pruning of C-style constructs
* Remove unused lap code in Garmin
Unrelated, but required to build on Mac
* Apply Mac runner updates per active topics from runner images bugreports.
It's my belief there are transient problems in the GitHub-provided images (linked in this CL) but this bulletproofs our installation, so I'm rolling with it.