CouplingMap should be iterable

[nonhermitian]

What should we add?

BackendV2 objects return a CouplingMap object as the coupling_map. The old list-based coupling_map allowed for simple iteration, such as:

for edge in backend.coupling_map:
    do stuff here

It would be nice if this same behavior could be done using CouplingMap objects. Currently one gets:

TypeError: 'CouplingMap' object is not iterable

[jakelishman]

There's .get_edges (or edge_list or something) on it.

[nonhermitian]

It also does not present any difficulty to give easier access to the primary data for CouplingMap in an easy manner, and solve issues like #8865 at the same time.

[jakelishman]

That's fair - I'm not saying we can't add the magic method, just that in the interim, the iterable form does exist.