[red-knot] Support `@typing.overload` and overloaded callable types

[carljm]

This is a tracking issue to add support for @typing.overload callables.

Reference spec: https://typing.python.org/en/latest/spec/overload.html

Work items

• Represent overloaded callables (functions, methods, etc.) in the type system ([red-knot] Add support for overloaded functions #17366)
• Check assignability / consistent subtyping between overloaded callable and other (possibly overloaded) callable types ([red-knot] Add support for overloaded functions #17366)
• Implement other relation methods for overloaded definitions
  • Equivalence ([red-knot] Support overloads for callable equivalence #17698)
  • Support gradual equivalence for an overloaded callable ty#105
• Implement the overload call site evaluation algorithm ty#104
  • Try: handle call semantics to overloaded functions as intersection of callables ([red-knot] Update call binding to return all matching overloads #17618)
• [red-knot] Support typing.get_overloads #17779
• Update property tests to generate overloaded callables, if possible (refer to [red-knot] Support @typing.overload and overloaded callable types #15383 (comment))
• Raise diagnostic for invalid overloaded definitions
  • If there are < 2 overloaded definitions ([red-knot] Check for invalid overload usages #17609)
  • If there is no implementation except in in stub files, protocols, and abstract methods within abstract base classes ([red-knot] Check overloads without an implementation #17681)
  • Check for overlapping overloads ty#103
  • Check implementation consistency for an overloaded function ty#109
  • (Low priority) Decorator consistency between overloads and implementation ([red-knot] Check decorator consistency on overloads #17684)
• Check if any of the special cased overloaded signatures can be removed (refer to [red-knot] Support @typing.overload and overloaded callable types #15383 (comment))
• Update hover implementation for overloads to account for the matched signature ty#73
  • How to display overloaded signatures in reveal_type, hover, etc.? (See: Display of overloaded definitions ty#102)
• Update goto definition for overloads to go to either the matched signature or the implementation