Enforce PEP 698 (override decorator)

[ItsDrike]

PEP 698 has introduced a new typing.override decorator, and suggested that type-checkers add an option to enable strictly enforcing the usage of this decorator for any method override in all classes.

This decorator does 3 things for us:

1. It makes it very easy to immediately see which methods in a class are overriding some inherited method, and which methods are new, introduced by the current class.
2. Consider a scenario where we have a class Foo, that defines some method my_method, and a class Bar, which inherits from Foo, and overrides this method with some other custom implementation. What if the parent Foo class suddenly renamed the my_method method to my_cool_method. Once this happened, the Bar class would no longer be overriding the my_method, but rather defining it as a completely new method, and inheriting the renamed my_cool_method from Foo. What typing.override does is ensure that methods marked with it are in fact overrides, so in this scenario, if Bar.my_method was marked as override, there would be a typing error, informing you that my_method is not actually inherited from anywhere, and so the override is invalid.
3. The methods decorated with typing.override will inherit the original docstring, unless another one is explicitly set. This allows us to reduce the repetition of docstrings fairly significantly. This is even recognized by ruff's flake8-docstrings, so no ugly noqas everywhere.

While the 1st point may be nice, it's not hugely important, however the 2nd point this feature brings could be pretty nice to have enforced, and the 3rd point is also quite neat.

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This PR was originally only made to see how enforcing this rule would look in the code-base, and I wasn't really sure whether or not to actually enable this enforcement. However, right now, I feel pretty strongly that enabling this is a good idea, and so, the do-not-merge tag from this PR was removed.