[flang] Use the newly introduced AliasAnalysisOpInterface.

This revision uses the AliasAnalysisOpInterface introduced in
https://reviews.llvm.org/D144851 to set the tbaa attributes
of load and store ops. With the attribute it is also possible to
set the attribute on atomics as well as on memcopy and
memove intrinsics as soon as https://reviews.llvm.org/D144965
lands.

Reviewed By: vzakhari

Differential Revision: https://reviews.llvm.org/D145044