Add tutorial on Magic States

[KaranBaijal]

Summary

Adding tutorial on magic state distillation and operators.

Details and comments

• Brief overview on stabilizers and magic states
• Explained use of magic states
• Worked through an example of developing a magic state
• Explained other possibilities of magic states

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[Eric-Arellano]

Hi, pardon that this hasn't gotten a review yet. Thank you for making Qiskit better!

We're very soon archiving the qiskit-tutorials repository to simplify how we build our documentation. The tutorials will be built directly in https://github.com/Qiskit/qiskit-terra.

If you'd still be interested in landing this, could you please open up a new PR in Terra that adds to the folder docs/tutorials/circuits_advanced?

I unfortunately can't comment on whether the PR would be accepted or not because I don't know the underlying content well enough. But the repo is more actively maintained so should get a response, and I can help ping the relevant people if you haven't heard back.

Thanks for the PR! Lmk if you have any questions.