refactor(deps): removing fbjs dependency by creating a local module for invariant and warning

[mateoguzmana]

As part of #2333, invariant and warning are the last two dependencies in the project used from fbjs and removing them allows removing that external dependency.

In this PR:

• Local module for invariant and replacing the imports
• Local module for warning which had another dependency of emptyFunction hence it has been added as well.
• fbjs dependency has been removed from packages/react-native-web/package.json.

I can still see fbjs in the main package-lock.json as there are other packages within the repo that have react-native-web installed as a dependency, hence it might potentially be removed once that dependency is upgraded as well.

Ps: I did the replacement of warning in the same PR as it was fairly small, but happy to split this up in another PR if needed.

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