Add tests that validate the themes
With the code from feedbackd!94 (merged) we actually make sure that device themes load (instead of just checking the json):
meson test -v -C _build
...
1/7 oneplus,enchilada.json OK 0.03s
2/7 oneplus,fajita.json OK 0.03s
3/7 xiaomi,beryllium.json OK 0.02s
4/7 pine64,pinephone.json OK 0.48s
5/7 purism,librem5.json OK 0.48s
6/7 pine64,pinephone-pro.json OK 0.49s
7/7 samsung,midas.json OK 0.49s
Draft until the feedbackd MR landed. We can enable the checks in CI once the package reached the distros.