Extend default or all blocks with custom functionality

[cgross]

BlockNote is really impressive! Thank you for building such a great library!

Is your feature request related to a problem? Please describe.
I'm using BlockNote to build a note editor for researchers. They need to be able to source individual blocks (like to note where they found the information).

It would also be important that this feature work across block types. Potentially all block types but some could be excluded. For example, an image/audio/file block would also need to be sourced to where they're from but heading blocks wouldn't.

Describe the solution you'd like
I think I can provide a new button in the block side menu. That would set some props on the block that would include the source information. That all seems possible today (I think). Then I would need a way to render the source from the props at the end of the block. The rendered source would be a small footnote.

Something like a decorator around the render function of all blocks would be amazing. If there was a way to do something like:

useCreateBlockNote({
   blockDecorator: ({props, children}) => <div>{children}<div>{props.source}</div></div>
})

Describe alternatives you've considered
I tried to see if i could use a custom style or the custom DOM attributes but neither solution seemed workable.

Additional context
If this would be a desired feature by the BlockNote team, I could create a PR if it would be looked and potentially merged.

Bonus
[ ] I'm a sponsor and would appreciate if you could look into this sooner than later 💖