Add edgeql to go code generator

[fmoor]

This change implements the default behavior outlined in https://github.com/edgedb/edgedb/discussions/4244. All arguments and options to the generator command are left for future work along with query hashing.

The documentation, help text, and cmd/edgeql-go/testdata directory may be areas of interest for reviewers.

This is related to https://github.com/edgedb/edgedb-go/issues/182

[fmoor]

Is edgeql-go an appropriate name for the go codegen binary?

cc @1st1 @colinhacks

[fmoor]

~This PR still needs tests added.~

[fmoor]

Ready for review

[fmoor]

@divan and anyone else that would like, we would love to have early feedback from the community on this feature if you are interested in trying it out.

[fmoor]

Currently all generated query functions are public. I think they should be private by default. Then if people ask for it we can provide a mechanism to tell the generator to make query functions public on a per query basis.

[fmoor]

~TODO: I need to look at linked property support~