[GuillaumeRx]

Explanation

Third step of the output revamp: repeated per-package warnings become one warning with a list of packages.

• Functions now return what happened, and the core prints it once:
  • readProject returns packagesUsingRootTag. runRelease prints one warning for these packages before the front end starts.
  • The changelog functions return 'updated' | 'no-changelog' | 'no-updates'. Mode.prepare and Mode.apply turn these into Notice objects ({ title, items }).
• startRelease and applyRelease print the notices after their step with a new CliOutput.warnList method.
• The legacy mode, selectMode and determineInitialParameters no longer take output, because they no longer print.

References

• Part of the output revamp stack
• Depends on feat(create-release-branch): show actionable errors #160

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them