TASK: Replace usage of Neos.Node.inBackend(node)

[mficzel]

Resolves partly neos/neos-development-collection#4396

This pr replaces usage of Neos.Node.inBackend(node) which is removed here neos/neos-development-collection#4067 with Neos.Backend.isEditMode(request) || Neos.Backend.isPreviewMode(request)

To verify you can run the ui with the branch neos/neos-development-collection#4067 be aware that the changes to adjust the ui to the separation of the edit and preview endpoints are not part of this pr.

[mhsdesign]

even if this is more explicit, i wonder if its enough to either A: mostly use Neos.Backend.isEditMode(request) or reduce code written by introducing Neos.Backend.isBackend(request)

[mficzel]

@mhsdesign i think asking for "are you edit or preview mode" is much more explicit. I also thought about a separate inBackend method that returns (self::isEditMode(request) || self::isPreviewMode()) but abstained for now as i do not like the semantic of inBackend as beeing either edit or preview.

BTW: The previous semantic of Neos.Node.inBackend was even worse as it only checked that the node was not live.

[grebaldi]

I was able to test this successfully with #3571.

I included this change over there.

I'm not sure how to go about this. This PR cannot be merged without neos/neos-development-collection#4067 over at neos-development-collection having been merged first. neos/neos-development-collection#4067 however cannot be merged without further changes in the UI (see: ce395ca).

I would therefore suggest to close this PR in favor of #3571.

[mficzel]

Close this here as this needs to be redone.