Full client-side rendering of regions that contain components that need page contributions to work

[espen42]

When React4xp client-side renders a region, a second rendering step is inserted by the client (postfillRegions). This can fetch and insert rendered HTML for the XP components that are contained in the region.

But not their page contributions. Currently, it's not possible in XP to fetch a particular component's page contributions from the client side (and it's provent fairly difficult to build a custom service for it) - only the HTML.

This means:

• It's possible for React4xp to server-side render entries with <Regions> and have the XP components get the page contributions they need (e.g. client-side rendered React4xp entries etc),
• Vice versa: It's possible to client-side render <Regions> as long as they don't contain XP components that need page contributions,
• But the combination - client-side rendering that contain anything that needs page contributions, will fail. This includes React4xp entries in the regions unless they are server-side rendered and ONLY needs the HTML - i.e. don't need any react hydration or other client-side activation.