Summary:
This moves the test script that generates **all outputs using all generators** to a dedicated "generate-all" CLI. This allows us to use it via Buck, at FB and OSS.
Also renamed the target to be more specific: "rn_codegen" => "generate_all_from_schema"
Changelog: [Internal]
Reviewed By: hramos
Differential Revision: D24513995
fbshipit-source-id: 8435d3d065718eb1309c1c61fe28fb592787311a
Kevin Gozali