More sophisticated tests for graph state backend internal

[Naphann]

Although we have a few test cases in Gs_qubit_internal_graph_test.cc that check properties of graph state manipulation such as adding edges, local complementation, measurements, and gate application. The current test cases are not enough to detect some propagation errors in the local complementation of large graphs or invariants under the rearrangement of measurement orders.

Objective:

We should at least have all possible combinations of measurement order of 1-round purification protocols (up to 3-4 qubits). We could split this into multiple smaller issues as well.

suggested list:

• 16 possible Bell pairs with single purification X or Z
• random graph and check local complementation
• check random stabilizer circuit (with mid-circuit measurement) results against other stabilizer simulators
• entanglement swapping (2-5 hops)
• counterfactual measurements