Move fil-actor-interface crate from fil-actor-states repo

[sudo-shashank]

Summary

The fil_actor_interface crate currently resides in the fil-actor-states repo, but it should be moved into forest repo inside shim/actors.
This avoids the need to constantly re-release fil_actor_interface for minor changes that are only needed for us.
This crate is not being used by any external projects, so it makes sense to optimize the structure for internal use.

Completion Criteria

• All references to fil-actor-interface within the forest repository are updated to reflect shim/actors.
• The fil-actor-interface crate is successfully moved from the fil-actor-states and it builds successfully with the moved fil-actor-interface crate.
• The fil-actor-interface crate is removed from the fil-actor-states repository to avoid confusion

Additional Links & Resources

https://github.com/ChainSafe/fil-actor-states/blob/main/fil_actor_interface/Cargo.toml