[mypy] Annotate other/lru_cache and other/lfu_cache (#5755)

* Adds repr and doctest of current behavior linkedlist in other/lru_cache

* Blocks removal of head or tail of double linked list

* clarifies add() logic for double linked list in other/lru_cache

* expands doctests to compare cache and lru cache

* [mypy] annotates vars for other/lru_cache

* [mypy] Annotates lru_cache decorator for other/lru_cache

* Higher order functions require a verbose Callable annotation

* [mypy] Makes LRU_Cache generic over key and value types for other/lru_cache

+ no reason to force int -> int

* [mypy] makes decorator a classmethod for access to class generic types

* breaks two long lines in doctest for other/lru_cache

* simplifies boundary test remove() for other/lru_cache

* [mypy] Annotates, adds doctests, and makes Generic other/lfu_cache

See also commits to other/lru_cache which guided these

* [mypy] annotates cls var in other/lfu_cache

* cleans up items from code review for lfu_cache and lru_cache

* [mypy] runs mypy on lfu_cache and lru_cache