Putting the LibTTF tests into the LibGfx directory worked fine before,
but causes issues if we try and call this from Lagom. Also, it's tidier
to put LibTTF tests in a LibTTF directory. :^)
This is in Tests/LibTTF instead of Tests/LibGfx because Tests/LibGfx
depends on serenity's file system layout and can't run in lagom,
but this new test runs just fine in lagom.
