Instead of assuming that we should use the OSC 9 progress messages
whenever we run on serenity, add a show-progress=[true|false] option.
This lets us avoid seeing esc sequence spam in GitHub Actions logs.
The test-js reporter is arguably the nicest test runner / reporter that
exists in the serenity code base. To the goal of leveling up all the
other unit test environments, start a new LibTest library so that we
can share code and reporting utilities to make all the test systems
look and behave similarly.
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
