Add fuzzing testing setup

Corpus pruning minimizes the corpus produced by batch fuzzing by removing redundant items while keeping the same code coverage.

The continuous build task causes a build to be triggered and uploaded as a GitHub Actions artifact whenever a new push is done to main/default branch.

Continuous builds are used when a crash is found during PR fuzzing to determine whether the crash was newly introduced. If the crash is not novel, PR fuzzing will not report it. This means that there will be fewer unrelated failures when running code change fuzzing.

Batch fuzzing enables continuous, regular fuzzing on your latest HEAD and
allows a corpus of inputs to build up over time, which greatly improves the
effectiveness of fuzzing. Batch fuzzing can be run on a cron schedule.

Prevent warning: ISO C requires a translation unit to contain at least one declaration [-Wempty-translation-unit]