* op-program: store prestate versions in json files

* op-program: add function to read standard.json

* op-program: embed standard.json to make it importable

* ci: checkout op-program tag after parsing standard.json file

* ci: fix EXPECTED_PRESTATE_HASH env var export

* op-program: combine releases into one file with governanceApproved flag

* op-program: add unit test for prestate GetReleases

* ci: point op-program preimage test at new versions.json file