Expose Multi-File AST

[EagleoutIce]

As a follow-up to #873, such calls should also present the user with all ASTs at once by choice (e.g., by adding a MultiFile AST-Root node or by returning a map of ASTs).

[LukasPietzschmann]

Is there an ETA for this? If not, do you think that this is something I could do in an hour?

[EagleoutIce]

There is no ETA atm :/

But for sure go ahead! Its probably easiest do add a new meta-root node for the AST to consolidate files but still handle everything with the existing folds / visitors. The IdMap is already updated accordingly (but still subject to #628).

Feel free to try a PR for this!

On the cheaper side, it may be easier to simply store "other ASTs" as a special field that is carried on and then exposed with the network messages.

[LukasPietzschmann]

Alright, I'll try my best :)