[WIP] Added new set of action transforms

[PSXBRosa]

Description

Added three new transforms for transforming actions:

• ActionTransform: a base class
• ActionScaling: for scaling actions according to loc and scale (similar to the ObservationNorm transform)
• ActionNorm: for automatically rescaling actions into a [-1,1] range, following what was proposed in the issue this PR tries to solve

Motivation and Context

partially solves #1209

• [ ] I have raised an issue to propose this change (required for new features and bug fixes)

Types of changes

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• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds core functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Documentation (update in the documentation)
• [ ] Example (update in the folder of examples)

Checklist

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• [x] I have read the CONTRIBUTION guide (required)
• [x] My change requires a change to the documentation.
• [ ] I have updated the tests accordingly (required for a bug fix or a new feature).
• [ ] I have updated the documentation accordingly.