grouped packages propagate the change type based on ChangeType order

[tannerlyons]

Previously, they were ordered based on the filesystem's sort order. The change type of the last change file in the array of changes for a group would be propagated to all the change files in that group.

This PR figures out the max change type for the entire group and sets that into the calculatedChangeTypes for the packages in the group.

[ghost]

All CLA requirements met.

[tannerlyons]

Hey team - it's been a while. Do we think any movement can happen on this MR or should we stop waiting? Are there people we can reach out to? Again, this lib is great and we love it. We'd appreciate some expectation-setting if possible :)