refactor!: move code generation from build script to separate crate #415
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An alternative to #412 to close #411.
This moves the build script to a separate
gencrate (outside the main workspace). It writes generated files tosrc/genof the main crate.This is a breaking change only because the
protocfeature is removed.This also adds a
generateworkflow to push updated generated files when we update the substrait submodule. With the dependabot update PRs it should make it easy to keep things updated. The other jobs will also run code generation, so for submodule updates the first commit checks with the updated generated files (because the bot push normally can't trigger other workflows).