[gql_build] Build to cache

[smkhalsa]

I've been experimenting with the builders, and I think we should build most of the files to the cache rather than to source. We have 10 builders now, and the number of generated files is overwhelming.

Do any builders other than req_builder and data_builder really need to be built to source?

[klavs]

I'm not sure about the implications of building to cache. If you play around and see it works well for cli, web and flutter, I'm open to such change.

An alternative I had in mind was something similar to part builder, where there is a post-processor which bundles built files into a single file. I think it is useful to see the genarated code.

I do not know what works the best, but I can certainly agree that there are too many files being generated.

Another thing to keep in mind is that some of the builders should be useful on their own, like AST builder which can be used in both Artemis and graphql-flutter.

[smkhalsa]

Another option is to build to a source subdirectory (such as __generated__). I believe this is the default for the Apollo Codegen.