feat: Add equivariance to ConjTensorSpecies

[jstoobysmith]

Adding an equivariance condition to ConjTensorSpecies, this will allow it to be used for conjugates of Weyl fermions etc.

[jstoobysmith]

@pariandrea FYI, you might be interested in this.

[github-actions]

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[nateabr]

Overall this was great to read, for a beginner(myself) the proofs of conjEquiv_equivariant and conjT_equivariant were particularly informative. I hope it gets merged soon.