[shape inference] Add shape inference func for Bucketize
Summary: ATT, to ensure output has the same dim type with the input. We need to find a more generic way though...
Test Plan: unit test
Reviewed By: ipiszy, khabinov
Differential Revision: D27690748
fbshipit-source-id: e53832c67b8ac86973c288d2d6b76ef8e5db14b9
