[AssumeBundles] Preserve Information in the inliner

Summary:
during inling Create and insert an llvm.assume with attributes to preserve them.
to prevent any changes for now generation of llvm.assume is under a flag disabled by default.

Reviewers: jdoerfert

Reviewed By: jdoerfert

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75825