feat: add state machine base

[willyrgf]

This is part of the v0.2 described here: #57

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This PR delivers:

• mfm_machine crate that will carry all state related implementation as an lib
• State module
  • State: enum describing all states possible and connecting them with the concrete implementation of StateHandler + StateConfig traits
  • StateError: enum describing all errors possible for each state return; it also enables us to check the StateErrorRecoverability of each error, which will be used to recover from errors using the State depends_on and dependency_strategy
  • Context: to handle the states context, where each state will receive a &mut impl Context to read/write
  • StateMachine: the executor of n-states handling the context's and transitions between states
  • states: sub-module of States that implements all states, currently just with simple states used to prove the design
• mfm_machine_macros: a crate that implements macros for the whole mfm_machine crate, currently implementing StateConfigReqs derive macro that implements all the required methods for StateConfig trait for states.