Typed-descriptors

1. Improved backing attribute logic: `__dict__` is used when available, slots are used otherwise.
2. Introduce `use_dict` and `use_slots` kwargs to constructors to enable manual determination of backing attribute logic.

Main changes:

1. Introduced the `TypedDescriptor` protocol, capturing the common logic of descriptors in the library.
2. Introduced a Mypy plugin to improve type inference on typed descriptors from this library.

**Full Changelog**: https://github.com/hashberg-io/typed-descriptors/compare/v1.1.0...v1.2.0

**Full Changelog**: https://github.com/hashberg-io/typed-descriptors/compare/v1.0.0...v1.1.0

**Full Changelog**: https://github.com/hashberg-io/typed-descriptors/commits/v1.0.0