[ci] Adds repo checks in main branch for batch release

[chunhtai]

This fixes main branch part of flutter/flutter#176433

The work left is adjusting cocoon to also run this check in release branch

The high level view of this pr.

1. Move ci_config.yaml and pending changelog parsing into RepositoryPackage and the parsed results are exposed as a getter method so that it can be shared between branch_for_release, repo_package_info_check, and version_check
2. The format error of ci_config.yaml and changelog files are reported in repo_package_info_check. The other 2 assume they are correct formatted and throw directly if they are not.
3. update the version_check to be able to handle batch release package

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter.
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or I have commented below to indicate which version change exemption this PR falls under¹.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style, or I have commented below to indicate which CHANGELOG exemption this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

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Footnotes

1. Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling. ↩ ↩² ↩³

[chunhtai]

no change to this part, just put the original code into the else case

[chunhtai]

Removed additional print to be more in sync with all the check in repo_package_info