Neos 9 Compatibility

[JamesAlias]

Follow up of https://github.com/sandstorm/MxGraph/pull/31

** THIS WILL BE A BREAKING CHANGE! ** -> and will be released as v4.

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

[JamesAlias]

One issue I found is that the LOCAL version does not provide the img assets for content like clipart. They are expected at for instance /neos/mxgraph/img/lib/clip_art/finance/Credit_Card_128x128.png

With drawioEmbedUrl: https://embed.diagrams.net it works and the images are inlined in the svg via base64.

So maybe we need to update the drawio assets for local embed.