This PR sets up the new integrated test/bench suite. It then migrates
all benchmarks and some related tests to the new suite. There's also
some documentation and some linting.
For now, a lot of the old tests are left alone so this PR doesn't become
even larger than it already is. Eventually, all tests should be migrated
to the new suite though so there isn't a confusing mix of two systems.
This PR updates the styling and wording of error messages produced in
inductive type declarations and anonymous constructor notation,
including hints for inferable constructor visibility updates.