testing/cura: upgrade to 5.2.0

This MR upgrades Cura and some of its dependencies to v5.2.0. This involved pretty substantial patching to the build system that these packages use due to Ultimaker recently switching to using conan to manage all dependencies. However, these builds do work from what I can tell. Still need to do more testing on actual Cura binary (ie actually try slicing a STL) and fix up some misc things.

TODO:

• Squash commits
• Add symlink from /usr/bin/cura to /usr/bin/cura_app.py to match the current package
• Look at other cura dependencies to ensure they're up to date
• Fix RPATH issue with py3-arcus
• Probably move py3-arcus to testing since nothing else depends on it
• Move stb to community since CuraEngine now depends on it
• Fix CuraEngine parabola assertion error
• Fix lint
• Add new packages to release monitoring

Future TODOs: Maybe come up with a more maintainable way to work with Conan? After these patches are in though, assuming their build process doesn't change again too much, everything looks reasonably maintainable.