[Flang][OpenMP][Lower] Use clause operand structures (#86802)

This patch updates Flang lowering to use the new set of OpenMP clause
operand structures and their groupings into directive-specific sets of
clause operands.

It simplifies the passing of information from the clause processor and
the creation of operations.

The `DataSharingProcessor` is slightly modified to not hold delayed
privatization state. Instead, optional arguments are added to
`processStep1` which are only passed when delayed privatization is used.
This enables using the clause operand structure for `private` and
removes the need for the ad-hoc `DelayedPrivatizationInfo` structure.

The processing of the `schedule` clause is updated to process the
`chunk` modifier rather than requiring two separate calls to the
`ClauseProcessor`.

Lowering of a block-associated `ordered` construct is updated to emit a
TODO error if the `simd` clause is specified, since it is not currently
supported by the `ClauseProcessor` or later compilation stages.

Removed processing of `schedule` from `omp.simdloop`, as it doesn't
apply to `simd` constructs.