[mlir][llvm] Translate alias scopes lazily

Change the LLVM dialect to LLVM IR translation to convert the alias
scope attributes lazily to LLVM IR metadata. Previously, the alias
scopes have been translated upfront walking the alias scopes of
operations that implement the AliasAnalysisOpInterface. As a result,
the translation of a module that contains only a noalias scope
intrinsic failed, since its alias scope attribute has not been
translated due to the intrinsic not implementing
AliasAnalysisOpInterface.

Reviewed By: zero9178

Differential Revision: https://reviews.llvm.org/D159187