--list and --only-errors options

[benjie]

Description

If you have errors in lots of sources, you might want to just list the source names so that you can clean them up.

Performance impact

Negligible

Security impact

None known.

Checklist

• My code matches the project's code style and yarn lint:fix passes.
• I've added tests for the new feature, and yarn test passes.
• I have detailed the new feature in the relevant documentation.
• I have added this feature to 'Pending' in the RELEASE_NOTES.md file (if one exists).
• If this is a breaking change I've explained why.