The default icons used in the pkgname output formats (∅,✔,𐄂) can
be hard to spot when scrolling through test output.

This PR adds the ability to pick a higher-visiblity/contrast set of
icons (🔳,✅,❌) by adding a `-hivis` suffix to either of the 'pkgname'
style formats.

Instead of a separate format name.

The other two hivis characters are in the dingbat unicode block, using a
code from this block from the third is nice because it increases the
chances that a font supports all 3 characters.

This character is also a bit less bright, which seems nice for skipped
tests, because the focus should be more on the failures.

Hivis icons