Define all Pauli strings (including rows of parity check matrices) in [X|Z] format

[perlinm]

On net, this should reduce mental load and confusion. Symplectic inner products between two Pauli strings are now computed with string_a @ qldpc.objects.conjugate_xz(string_b).

Flagging this PR for

• @jmlarson1 because this may change node labels in Tanner graphs (in which nodes = data or check qubits, and edges are drawn between check qubits and the data qubits they address), and
• @qodesign because this PR changes something I previously said here (though I have since updated the comment to be consistent with the changes in this PR). When constructing a custom QuditCode, you should now specify stabilizers in [X|Z] form, where the first num_qubits entries of a vector (that represents a stabilizer) specifies its Pauli-X support, and last num_qubits entries of the vector specifies its Pauli-Z support.

[jmlarson1]

Thanks for the heads-up. I'll start from scratch working from main and I'll save any past results for safe-keeping (in case I can't reconstruct them with this new format)