* Revert "port more ops to JSON (#2809)"

This reverts commit 137f3373.

* Revert "port ops to JSON: compiler, errors, fetch, files (#2804)"

This reverts commit 79f82cf1.

* Revert "Port rest of os ops to JSON (#2802)"

This reverts commit 5b2baa5c.

Just some clean up reorganization around flatbuffer/minimal dispatch
code. This is prep for adding a JSON dispatcher.

Note cli/dispatch_minimal.rs ops are not yet included in cli/ops.

This is part of work towards #2730