[Feature Request] Print execution summary at the end of output

[kyu08]

Thank you so much for maintaining awesome E2E testing tool! Scenarigo has greatly improved the development productivity of me and my team.

Issue to be solved

• If you run a lot of scenarios and some tests fail, it can be a bit tedious to scroll through the long output to see which files failed.
• In order to know how many of the tests that were run failed, it is also necessary to scroll through the long output and count the number of failed tests.

Solution

Print test execution summary like below at the end of output.

11 tests run: 9 passed, 2 failed, 0 skipped

Failed tests:
  - scenarios/scenarigo-1.yaml
  - scenarios/scenarigo-2.yaml

Implementation

• I tried to implement this feature.(#395)
• If this feature request is acceptable, I will polish up this PR on some points listed in the description of the PR.