Improve the mutation-report UI

[Rqnsom]

We could have the display in two modes:

• all mutants survived
• at least one mutant survived

The move-mutation-test --parse-coverage report.txt could be added for this

Steps:

• [x] https://github.com/eigerco/move-spec-testing/pull/35
• [x] https://github.com/eigerco/move-spec-testing/pull/36
• [x] https://github.com/eigerco/move-spec-testing/pull/39
• [x] https://github.com/eigerco/move-spec-testing/pull/40

[Rqnsom]

https://github.com/eigerco/move-spec-testing/pull/40