Display number of skipped tests

[ad-si]

Currently it does not say how many tests were skipped:

Running 148 tests. To reproduce these results, run: elm-test --fuzz 100 --seed 132114825190419

TEST RUN INCOMPLETE because Test.skip was used

Duration: 388 ms
Passed:   148
Failed:   0

[mpizenberg]

This behavior is due to the output of the fromTest function in elm-explorations/test. It would require a change there to also pass the result of countAllRunnables distribution.skipped to the Skipping custom type variant.

[harrysarson]

Blocked on elm-explorations/test#161.