[sanitizer] Implement __sanitizer_get_allocated_size_fast

The primary motivation for this change is to allow FreeHooks to obtain
the allocated size of the pointer being freed in a fast, efficient manner.

Differential Revision: https://reviews.llvm.org/D151360

GitOrigin-RevId: 7639265af4547c0330d5949f0da8f92e9b83f6b0