[hab3_merge] Add Skills for the robot to move forward/backward and turn

[xavierpuigf]

Motivation and Context

Add skills to allow low level movement for the robot. This is needed so that the robot can make way to the human when about to collide.

How Has This Been Tested

Tested with hl_fixed policy, verifying that the agent would turn when the skill is called.

Types of changes

• [Experiment] A pull request that add new features to the habitat-baselines training codebase. Experiments Pull Requests can be any size, must have smoke/integration tests and be isolated from the rest of the code. Your code additions should not rely on other habitat-baselines code. This is to avoid dependencies between different parts of habitat-baselines. You must also include a README that will document how to use your new feature or trainer. You will be the maintainer of this code, if the code becomes stale or is not supported often enough, we will eventually remove it.

Checklist

• My code follows the code style of this project.
• I have updated the documentation if required.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes if required.

[ASzot]

This looks good, but if we are merging into main, we should have a test for this new skill.

[xavierpuigf]

Thanks @ASzot ! I added pytests for the new skills