This patch adds support to emit default declare mappers for implicit
mapping of derived types when not supplied by user. This especially
helps tackle mapping of allocatables of derived types.

Currently we generate these bounds in the MapInfoFinalization.cpp pass
as it seems there's a missing case for character strings/arrays (length
parameter) in the DirectiveCommons bounds generation functionality
OpenMP uses for it's map operations.

This PR tries to add this case to the DirectiveCommons function and
remove the need for the bounds generation in the MapInfoFinalization
pass, so that we are generating the bounds in the same place most other
bounds are generated.

Currently we handle BoxChars separately and a little differently to the
other BoxType's, however realistically they can be handled the same and
should be to simplify the pass as much as we can.

See
https://discourse.llvm.org/t/psa-opty-create-now-with-100-more-tab-complete/87339.

I plan to mark these as deprecated in
https://github.com/llvm/llvm-project/pull/164649.

This PR shifts from using the LLVM OpenMP enumerator bit flags to an
OpenMP dialect specific enumerator. This allows us to better represent
map types that wouldn't be of interest to the LLVM backend and runtime
in the dialect.

Primarily things like
ref_ptr/ref_ptee/ref_ptr_ptee/atach_none/attach_always/attach_auto which
are of interest to the compiler for certrain transformations (primarily
in the FIR transformation passes dealing with mapping), but the runtime
has no need to know about them. It also means if another OpenMP
implementation comes along they won't need to stick to the same bit flag
system LLVM chose/do leg work to address it.

- Add CLOSE map flag when USM is required.
- use_device_ptr: prevent implicitly expanding member operands.
- Fixes test offload/test/offloading/fortran/usm_map_close.f90.

This PR adds deferral of descriptor maps until they are necessary for
assumed dummy argument types. The intent is to avoid a problem where a
user can inadvertently map a temporary local descriptor to device
without their knowledge and proceed to never unmap it. This temporary
local descriptor remains lodged in OpenMP device memory and the next
time another variable or descriptor residing in the same stack address
is mapped we incur a runtime OpenMP map error as we try to remap the
same address.

This fix was discussed with the OpenMP committee and applies to OpenMP
5.2 and below, future versions of OpenMP can avoid this issue via the
attach semantics added to the specification.

This PR adds support for nested derived types and their mappers to the
MapInfoFinalization pass.

- Generalize MapInfoFinalization to add child maps for arbitrarily
nested allocatables when a derived object is mapped via declare mapper.
- Traverse HLFIR designates rooted at the target block arg and build
full coordinate_of chains; append members with correct membersIndex.

This fixes #156461.

Reverts llvm/llvm-project#160116

This PR adds support for nested derived types and their mappers to the
MapInfoFinalization pass.

- Generalize MapInfoFinalization to add child maps for arbitrarily
nested allocatables when a derived object is mapped via declare mapper.
- Traverse HLFIR designates rooted at the target block arg and build
full coordinate_of chains; append members with correct membersIndex.
  
This fixes #156461.