Extract boilerplate code into Routed base classes

[RobbeSneyders]

As mentioned in #1588, we're repeating a lot of boilerplate across the middlewares. This PR extracts this boilerplate into shared base classes. Feel free to propose better naming for them :slightly_smiling_face:

I had to revert the order of Middleware - Api - Operation to Operation - Api - Middleware due to dependencies in the typing.

[coveralls]

Pull Request Test Coverage Report for Build 3130067976

• 144 of 154 (93.51%) changed or added relevant lines in 7 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 95.243%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
connexion/middleware/routing.py	25	27	92.59%
connexion/middleware/abstract.py	64	72	88.89%
<!--	Total:	144	154

Totals
Change from base Build 3129982881:	0.03%
Covered Lines:	2843
Relevant Lines:	2985

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💛 - Coveralls