Add validation for environment variables for Fantom (#52779)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/52779

Changelog: [internal]

Adds validation for Fantom environment variables at runtime, to catch typos or variables that no longer have an effect.

Reviewed By: rshest

Differential Revision: D78803045

fbshipit-source-id: efb28a4f3fd6a4be35fb525d91fb093a1e88f7e4