[mlir][openacc] Add OpenACC translation to LLVM IR (enter_data op create/copyin)

[mlir][openacc] Add OpenACC translation to LLVM IR (enter_data op create/copyin)

This patch begins to translate acc.enter_data operation to call to tgt runtime call.
It currently only translate create/copyin operands of memref type. This acts as a basis to add support
for FIR types in the Flang/OpenACC support. It follows more or less a similar path than clang
with `omp target enter data map` directives.
This patch is taking a different approach than D100678 and perform a translation to LLVM IR
and make use of the OpenMPIRBuilder instead of doing a conversion to the LLVMIR dialect.

OpenACC support in Flang will rely on the current OpenMP runtime where 1:1 lowering can be
applied. Some extension will be added where features are not available yet.

Big part of this code will be shared for other standalone data operations in the OpenACC
dialect such as acc.exit_data and acc.update.

It is likely that parts of the lowering can also be shared later with the ops for
standalone data directives in the OpenMP dialect when they are introduced.

This is an initial translation and it probably needs more work.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D101504