Add exhaustive/extensive tests

[tgross35]

Add a generator that will test all inputs for input spaces u32::MAX or smaller (e.g. single-argument f32 routines). For anything larger, still run approximately u32::MAX tests, but distribute inputs evenly across the function domain.

Since we often only want to run one of these tests at a time, this implementation parallelizes within each test using rayon. A custom test runner is used so a progress bar is possible.

Specific tests must be enabled by setting the LIBM_EXTENSIVE_TESTS environment variable, e.g.

LIBM_EXTENSIVE_TESTS=all_f16,cos,cosf cargo run --features test-multiprecision --release

Testing on a recent machine, most tests take about two minutes or less. The Bessel functions are quite slow and take closer to 10 minutes, and FMA is increased to run for about the same.

This uses the libtest_mimc harness so a progress bar can be printed. Example:

running 90 tests
test mp_extensive_acos       ... ignored, extensive tests are only run if specified in RUST_LIBM_EXTENSIVE
test mp_extensive_acosf      ... starting extensive tests for `acosf`
[9m  100%] #################### acosf 4,294,967,295/4,294,967,295: 7,672,836.6102/s eta 0s
ok
test mp_extensive_acosh      ... ignored, extensive tests are only run if specified in RUST_LIBM_EXTENSIVE
test mp_extensive_acoshf     ... starting extensive tests for `acoshf`
[5m  73 %] ###############----- acoshf 3,139,620,000/4,294,967,295: 3,544,521.3401/s eta 5m (1.6715916e36,)

Recreated from #364.

[tgross35]

I have been using this for a few weeks and it has worked pretty great. Going to merge this so the exhaustive CI checks become available for all PRs.