Initial Implementation of Supersymmetric Functions And Multiplicative Bases

[25shriya]

This PR focuses on an initial implementation of supersymmetric functions and their multiplicative bases. This includes the powersum, homogeneous and elementary supersymmetric functions.
Check relevant issue.
@tscrim

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

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[25shriya]

@tscrim lift() and retract() are now working. However, there are some issues:

1. TestSuite() fails for the antipode test (all 3 bases). This is something I observed after I updated SageMath, although I didn't touch the code for any of it.
2. I am also unable to see the documentation although the super_sf module has been added in the appropriate places (also in the module index as we discussed.)
3. I tried to write the antipode_on_basis method for the TensorProductCategory class for SuperSymAlgebraBases. However, I am not able to access those methods. (although p.tensor_square().antipode_on_basis?? returns the right source.) It has been commented for the time being