ENH: Simulation Save and Load in JSON Files

[phmbressan]

Pull request type

• [X] Code changes (bugfix, features)

Checklist

• [X] Tests for the changes have been added (if needed)
• [ ] Docs have been reviewed and added / updated
• [X] Lint (black rocketpy/ tests/) has passed locally
• [X] All tests (pytest tests -m slow --runslow) have passed locally
• [ ] CHANGELOG.md has been updated (if relevant)

New behavior

This PR improves rocketpy encoding and introduces decoding functionalities. The way this works is:

• If the is a to_dict or from_dict method, they are used to perform the (de)encoding;
• Otherwise, a default encoding of all vars() and constructor based decoding is done.

Breaking change

• [ ] Yes
• [X] No

Additional information

PR #679 should be merged first.

Here are some of the steps that could be improved:

• [ ] Verify why the test for hybrid motor flight requires higher tolerances;
• [ ] Test if all of the atmospheric models of Environments can be decoded without requiring re-read of files or API;
• [ ] Evaluate whether we should encode outputs or only the minimum required information to decode the class from its init;
• [ ] (Optional) Expand implementation to AirBrakes + Controllers and new classes.

Some important remarks:

• The simple getting started simulation is essentially identical comparing the store & load, the only difference is the random lag and noise from Parachute class. I could not found a simple solution to reset those and always get the same results.