Support Substrait's VirtualTables

[Blizzara]

Which issue does this PR close?

Closes #10530

This is my first (but hopefully not last!) contribution to DataFusion, and I'm pretty new with Rust as well - so all feedback on both style and details is very much welcome!

Rationale for this change

What changes are included in this PR?

Adds support for Substrait's VirtualTables, ie. tables with data baked-in into the Substrait plan instead of being read from a source.

Adds conversion in both ways (Substrait -> DataFusion and DataFusion -> Substrait)

Are these changes tested?

Tested through round-trip tests, similar to other Substrait support.

Are there any user-facing changes?

• More support through Substrait

[alamb]

Thanks @Blizzara -- I started the CI on this PR

[Blizzara]

@jonahgao @alamb I think this is ready by me :)

[Blizzara]

@jonahgao Thanks for the review - I pushed a new version but it builds on top of https://github.com/apache/datafusion/pull/10622 and https://github.com/apache/datafusion/pull/10640 so will need those merged and this rebased first before this PRs looks clean.

This is mostly what it used to be with one more major change: I removed passing the datatype into from_substrait_literal and instead do the same thing with names as I did for from_substrait_type. That maybe seems a bit cleaner (even though I dislike the name handling, but I don't see a better way to deal with it based on how it works in Substrait :/)

[Blizzara]

@jonahgao @alamb this last one is ready now too :)