Add tool execution summary

[neob91-close]

I often don't know at a glance whether all checks succeeded or failed (need to scan all output, or check the exit code). I thought a summary would be useful to humans in determining at a glance whether checks succeeded or failed.

Screenshots:

• Checks failed
• Checks passed

[neob91-close]

@vtclose Will bumping lintlizard version release it automatically?

[AlecRosenbaum]

Nope, we'll release it manually after it's merged

[neob91-close]

I released it. Due to releaserabbit issues, the version got bumped twice inadvertently, but only 0.24.0 was pushed to PyPI.