See#791

I think it's better to introduce these as a number of separate rules.
It makes it easier for people to opt in to the rules, and keeps each implementation small and focused.
This also makes it easier and faster to build and release, as we can build and release smaller rules instead of releasing one monolithic rule.

Based off of#1643

This rule does two things:

1. it checks all function returns and errors if you returnany.
2. if the type is not explicitly any, it compares a return type with the function signature's return type, comparing the generic parameters to ensure no unsafe assignment is occurring:
   • i.e. this will error in the lint rule, but is "safe" in TS
     function foo(): Set<string> { return new Set<any>([1]) }