[MLIR][OpenMP] Refactoring createTargetData in OMPIRBuilder

Key changes:
  - Refactor the createTargetData function to make use of the emitOffloadingArrays and emitOffloadingArraysArgument functions to generate code.
  - Added a new emitIfClause helper function to allow handling if clauses in a similar fashion to Clang.
  - Updated the MLIR side of code to account for changes to createTargetData.

Depends on D149872

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D146557