9.0: Rebuild editPreviewModes

[mhsdesign]

WIP writeup ...

currently the editPreviewMode is available via:
node.context.currentRenderingMode -> UserInterfaceMode

and it will be added to the GlobalCacheIdentifiers

neos-development-collection/Neos.Neos/Resources/Private/Fusion/Override/GlobalCacheIdentifiers.fusion

Line 9 in 30c8df2

editPreviewMode = ${documentNode.context.currentRenderingMode.name}

The neos ui allows to change the preview modes, but this change affects the whole session.

---

This has now been temporarily removed with the new CR, as context is dumped, and the nodeInfo helper (a replacement for node.inBackend https://github.com/neos/neos-ui/blob/f501f800f28c3523a90d52f807148cddf54ebb79/Classes/Fusion/Helper/NodeInfoHelper.php#L530) doesnt know anything about the preview mode too.

We should consider passing the currentRenderingMode via request parameter.
Question is, how we handle caching and allow uncached segments to work.

(fx. opening the preview in the iframe should not have the node uris converted, but when using the preview button (effectively the same route) the uris should function normally and be converted)

Im hoping to also fix these bugs in the same run:

• Node URIs are not converted in frontend preview of workspaces #2347
• Allow edit and preview in separate windows #965

[mhsdesign]

Close as dub of #4086