Make sure hyperedges are correctly handled

[quantumjim]

Steps to reproduce the problem

from qiskit_qec.decoders import DecodingGraph
from qiskit_qec.circuits import ArcCircuit

code = ArcCircuit([(0,1,2),(2,3,4),(4,5,6),(6,7,8),(8,9,0)],1)
dg = DecodingGraph(code)
print(dg.hyperedges)

What is the current behavior?

For some codes, such as a periodic repetition code, boundary nodes should be part of a hyperedge. But the hyperedges generated in the above only possess a single edge each (and hence are just normal edges).

What is the expected behavior?

The hyperedges should be checked and made to work properly for ArcCircuit and the stim compatibility.