Automagic dispatch for universal functions

[IvanIsCoding]

Follow up of #882, albeit more agressive on shortening the boilerplate amount of code for universal functions

This PR introduces a new _rustworkx_dispatch decorator that:

• Creates the singledispatch for func
• Automatically registers digraph_func for PyDiGraph
• Automatically registers graph_func for PyGraph

The decorator is based on the original functools.singledispatch. It should simplify the amount of code we need to write an universal function. It does add a little bit of "magic" with functools and importlib, but overall it should be maintainable

[coveralls]

Pull Request Test Coverage Report for Build 7997454293

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 6 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.03%) to 96.483%

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Files with Coverage Reduction	New Missed Lines	%
src/shortest_path/all_pairs_bellman_ford.rs	6	95.53%

Totals
Change from base Build 7996586980:	-0.03%
Covered Lines:	16815
Relevant Lines:	17428

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💛 - Coveralls

[IvanIsCoding]

This is ready for review

[jakelishman]

I scanned through all this and all the re-registrations look right to me, including the is_isomorphic_node_match rewrite to not be a direct dispatcher itself.

I personally avoid magic name inference like this, but this will fail loudly and immediately at import time if something's not available, so I'd agree it should be maintainable enough (and the line-count reduction is nice for sure).

My ticks don't count on rustworkx, but you can have one in principle (with or without the importlib change).

[mtreinish]

LGTM, we end up doing this a lot so abstract away the boilerplate makes a lot of sense here.