[flang][openmp] Add General Semantic Checks for Allocate Directive

[flang][openmp] Add General Semantic Checks for Allocate Directive

This patch adds semantic checks for the General Restrictions of the
Allocate Directive.

Since the requires directive is not yet implemented in Flang, the
restriction:
```
allocate directives that appear in a target region must
specify an allocator clause unless a requires directive with the
dynamic_allocators clause is present in the same compilation unit
```
will need to be updated at a later time.

A different patch will be made with the Fortran specific restrictions of
this directive.

I have used the code from https://reviews.llvm.org/D89395 for the
CheckObjectListStructure function.

Co-authored-by: Isaac Perry <isaac.perry@arm.com>
Reviewed By: clementval, kiranchandramohan

Differential Revision: https://reviews.llvm.org/D91159