Refactor: Duplicate functionality in basis and standard basis

[vprusso]

We have the same functionality in the states/basis.py file and the matrices/standard_basis.py. We should restrict to having just one, preferably the latter of standard_basis.py.

This would involve removing basis.py as well as all references, tests, for this. Additionally, we will want to use standard_basis in place of anywhere we currently use basis.