Per package CPM_DOWNLOAD controls and consistent option behaviour

What's Changed

• Fix comment out-of-sync with modified code by @danra in #321
• Unified GitHub workflow for tests on major operating systems by @iboB in #326
• [Example] Disable JSON tests being included in ctest by @Vinpasso in #329
• Remove badges from readme by @TheLartians in #327
• Initial version of integration tests by @iboB in #330
• Allows set/set(CACHE) to behave the same as set(X)/option(x) by @robertmaynard in #335
• Use CMake 3.14+ documented way to pass the source dir -S. by @robertmaynard in #337
• Fix beginner’s trap / fix broken example for nlohmann/json by @Tobi823 in #338
• List of contributors by @iboB in #340
• Some typo fixes. by @bilke in #341
• Add per package CPM_DOWNLOAD controls by @robertmaynard in #336

New Contributors

• @danra made their first contribution in #321
• @Vinpasso made their first contribution in #329
• @robertmaynard made their first contribution in #335
• @Tobi823 made their first contribution in #338
• @bilke made their first contribution in #341

Full Changelog: v0.34.3...v0.35.0

Thanks to everyone who contributed for these updates!