rpc-state-reader refactor

[JulianGCalderon]

This PR changes our RpcStateReader to use sequencer's RpcStateReader. This implied the following changes:

• blockifier_state_reader.rs and rpc_state.rs files were merged into a single file reader.rs, which uses sequencer's RpcStateReader
• Auxiliary RPC objects where moved to another file objects.rs. This was not neccesary, but I think it makes the implementation clearer.
• blockifier_state_reader used to contain execute_... functions to replay a transaction with blockifier. I moved those functions to a different file execution.rs so that they are separate from the reader (they are independent). Shouldn't they belong to the replay crate?

Most of the changes in this PR comes from moving files around, not new features. This PR does not add functionality

This PR depends on: https://github.com/lambdaclass/sequencer/pull/14

I've tested this changes with a few blocks and it seems to be working properly

[github-actions[bot]]

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