Write public guide for using BitArray directly

[SamFerracin]

This PR updates the guide about inputs and outputs of primitives to show how to make the best use of BitArray objects

[review-notebook-app[bot]]

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[qiskit-bot]

One or more of the following people are relevant to this code:

• @kaelynj

[ihincks]

Thanks @SamFerracin , I will leave a review next week.

[abbycross]

Work was finished in #3219