!!!FEATURE: Neos 9.0 compatible

[markusguenther]

Making the Backend part and Neos-UI part Neos 9.0 compatible. This is a followup of @Jan3k3y PR!

[markusguenther]

Fixed the error in 920bca4
But still dont find the Nodes. So will ask for help here.

[markusguenther]

I found the problem and made a mistake using the Graph. Now I can easily find diagrams and reuse them.
And guess what? The UI errors are also gone!

mxgraph.mp4

[markusguenther]

When Neos 9 is released we can adjust the beta20 constraint and hope it is ok that I use LazyDataSource already in a new major, as it will be a major version for 9.0 I bet.

[JamesAlias]

FYI: I'm working on it over here and will commit to this PR when I'm done: https://github.com/JamesAlias/MxGraph/tree/neos9

I could spam my WIP commits here, but I thought I keep this PR clean for now^^

Easy way to see changes: markusguenther/MxGraph@neos9...JamesAlias:MxGraph:neos9

[JamesAlias]

@markusguenther I created a PR with all the fixes and adjustments: markusguenther#1

I am not sure about using inline styles for alignment, but it works.

There are 2 TODOs that can be removed, but I feel like the PropertyValuesToWrite ValueObject would be easier to handle if it would provide the two functions:

• function hasProperty(PropertyName $propertyName): bool
• function getProperty(PropertyName $propertyName): mixed

[markusguenther]

Closed in favour of #32