Add memoization to StagedPassmanager

[pedrorrivero]

Summary

Simplifies code and improves readability by introducing memoization for expanded_stages in StagedPassmanager through the cached_property decorator in functools. @mtreinish @jakelishman

Details and comments

1. Removes need to call parent class __setattr__.
2. Removes pylint ignores.
3. Removes need to set self._expanded_stages attribute.
4. Maintains efficiency and functionality thanks to self.expanded_stages immutability.

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[coveralls]

Pull Request Test Coverage Report for Build 2590459825

• 11 of 14 (78.57%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 83.961%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/transpiler/passmanager.py	11	14	78.57%

Totals
Change from base Build 2585369189:	0.002%
Covered Lines:	55787
Relevant Lines:	66444

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💛 - Coveralls

[jakelishman]

This feels like a lot of complexity - _validate_init_kwargs is always called during __init__, so the expanded_stages object is always created anyway. If the issue is purely about __setattr__, then it would be better to just handle that in __setattr__: something like having both self.expanded_stages accesses be getattr(self, "_expanded_stages", ()) would sidestep the issue - if _expanded_stages hasn't yet been set, then it'll just default to an empty set, and __setattr__ will always do the right thing.

cached_property is effectively just a different way of sidestepping the underlying __setattr__ issue - it directly gets the __dict__ from the object it's attached to, and then does its gets and sets into that rather than using the regular structures.

[jakelishman]

This has merge conflicts due to the rewriting of the pass-manager structures in #10124 and #10127. Given my above comment, I'm not super clear that the additional complexity added by this PR is worthwhile, but if this is something you feel strongly should be included in the StagedPassManager, feel free to re-open this PR / open a new one targetting the new structure (as appropriate).