The previous implementation added a section_title to the package_info
which was also stored in the packages.json. The section_title is now
provided to the PackageModel as an extra optional argument.
Contributes to CURA-8558
By providing a `section_title` with a string to the `package_data`
packages can be subdivided in sections, each with its own header.
For remote packages this will be `None` and therefore no sections are
created there.
Contributes to CURA-8558
