HACK: Static detection of infinite sequences

HACK: Static detection of infinite sequences

Summary:
Certain operations should not be performed on infinite sequences
(e.g. sorting, left-folds, summation).  In some cases, we can
detect that a sequence is infinite at compile-time and provide
a static_assert to prevent such dangerous operations.

Test Plan:
Manually created cases where the operation should
be disallowed.  Compiler correctly raised an error.

Reviewed By: tjackson@fb.com

FB internal diff: D740011