Error gen projection basis must be Basis object

[pcwysoc]

Describe the bug Error generator projections require a Basis object and do not work with a basis name, i.e. 'pp'. This is not the expect behavior as listed in the documentation. The issue appears to be with how the errorgen_and_projections function in reportables.py handles basis information.

Environment (please complete the following information):

• pyGSTi version feature-qiskit-mcm
• python version 3.10
• OS Ventura 13.6.7