Config with plone.meta and drop pkg_resources

[gforcada]

See plone/Products.CMFPlone#4126

Before dropping pkg_resources there is a slew of commits that handle the usual plone.meta configuration 😄

Warning

This pkg_resources replacement is a bit more involved, so testing with actual code would be useful, as test coverage for that part does not exist 🤦🏾

[mister-roboto]

@gforcada thanks for creating this Pull Request and helping to improve Plone!

TL;DR: Finish pushing changes, pass all other checks, then paste a comment:

@jenkins-plone-org please run jobs

To ensure that these changes do not break other parts of Plone, the Plone test suite matrix needs to pass, but it takes 30-60 min. Other CI checks are usually much faster and the Plone Jenkins resources are limited, so when done pushing changes and all other checks pass either start all Jenkins PR jobs yourself, or simply add the comment above in this PR to start all the jobs automatically.

Happy hacking!