Implement new ContentBrowserWidget

[petschki]

This targets Plone 6.1 only and should be released as 4.0.0 ... Plone 6.0 stays on 3.x (TODO: make branch done)

related PR:

• plone.app.z3cform (Implement ContentBrowserWidget for the new pat-contentbrowser pattern plone.app.z3cform#197)
• mockup (pat-contentbrowser implementation mockup#1377)
• plone.staticresources (pat-contentbrowser resources plone.staticresources#336)

[mister-roboto]

@petschki 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!

[petschki]

@gforcada this depends on a source checkout of plone.app.z3cform ... is there a common solution for meta tests to get source checkouts for certain packages?

[petschki]

meta tests cannot be configured with checkouts (at least I could not) ... jenkins is green though.