Adds `OperationSpaceController` to docs and tests and implement corresponding action/action_cfg classes (#913)

# Description

This PR adds the `OperationalSpaceController` to the docs and provides
some tests for its parametric features. Moreover, it implements the
corresponding `OperationalSpaceControllerAction` and
`OperationalSpaceControllerActionCfg` classes so they can be used with
manager-based environments.

Fixes #873 

## Type of change

- Bug fix (non-breaking change which fixes an issue)
- New feature (non-breaking change which adds functionality)
- This change requires a documentation update

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there
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Signed-off-by: Özhan Özen <41010165+ozhanozen@users.noreply.github.com>
Co-authored-by: James Tigue <jtigue@theaiinstitute.com>
Co-authored-by: jtigue-bdai <166445701+jtigue-bdai@users.noreply.github.com>
Co-authored-by: Kelly Guo <kellyguo123@hotmail.com>