[Flang][OpenMP] Fix 'Internal: no symbol found' for OpenMP aligned and linear clause.

The initial approach was to go with changing parser nodes from `std::list<parser::Name>` to `OmpObjectList`, but that might have lead to illegal programs.
Resolving the symbols inside `OmpAttributeVisitor`.
Fix a couple of `XFAIL` tests.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D90538