Ignore unknown_shaped tensor in bound shape inference (#16916)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16916
Two fixes for maximum effort bound shape inference
1. Ignore failed and unknown shape
2. Add specialization for `SparseLengthsWeightedSumFused8BitRowwise`.
Reviewed By: ipiszy
Differential Revision: D14017810
fbshipit-source-id: 25cd68d35aa20b9ed077bdb562eb7f9deff0ab96
