Introduce Result class to allow a modern representation of failure cases

[johnthagen (John Hagen)]

For prior art, see:

• Result - returns 0.23.0 documentation

Though there are some drawbacks, such as not supporting exhaustive match ing due to a lack of @sealed.

• mypy plugin allows false positive error when exhaustively pattern matching on Result · Issue #1361 · dry-python/returns · GitHub

Also related to ADTs:

• GitHub - johnthagen/sealed-typing-pep: A PEP to add a `@sealed` typing decorator to Python
• Draft PEP: Sealed decorator for static typing