validate network definitions with `upgrades.json`

[LesnyRumcajs]

Summary

There's a shared source of truth we could use in Forest to assert the correctness of its network definitions. See the JSON at filecoin-project/core-devs#184

While having it as part of our build seems too much (especially since only a subset of the network is present), we can certainly include some validations in tests, i.e., check that the epochs are correct in the CI.

Completion Criteria

• Implement tests validating some of the properties of the network definitions we have - this includes network epochs and CIDs in the manifests.
• Ensure the tests are run in CI

Additional Links & Resources

[0xDevNinja]

Planning to cross-check Forest's HEIGHT_INFOS against the authoritative upgrades.json by vendoring it under build/ and adding a test that validates each Height variant. Will include a small allowlist for Forest-specific heights like WatermelonFix and Breeze. If a maintainer can assign this to me that would be great — otherwise I'll reference it via Closes #4941 in the PR.

— @0xDevNinja

[LesnyRumcajs]

After some consideration, this is probably not a valuable feature. Network upgrades need to be coordinated anyway and if anything, the aforementioned JSON file gets updated last. Thanks for your interest, though.