TST/CI: Initial setup tasks

[lucascolley]

From #14 (comment) :

• Add documentation for how to run the tests. (closed by CI: test macOS #19)
• Add test coverage like what was done in TST: add data-driven test #7 (closed by TST: generate coverage report #22)
• Use ccache in CI to save time. (closed by CI: set up ccache #23)
• Add error tolerance parquet files for more platforms and test in CI (CI: test macOS #19, CI: test windows #21)
• Workflows to update platform specific error tolerance parquet files for continuous improvement.
• Work on Allow changing the format of StringMaker<float> and StringMaker<double> catchorg/Catch2#2226 to improve floating point number formatting.