Add Fortran tests for named constants in data and firstprivate clauses

[Ryanpadrone]

Feature:
OpenACC 3.4 section 1.6 clarifies that a Fortran named constant (PARAMETER) is a valid var and may appear anywhere a var is permitted in OpenACC syntax, including:
• compute clauses such as firstprivate
• data clauses such as copyin, present_or_copyin, and create

What this PR adds
– This PR introduces a new Fortran V&V test file, acc_named_constant.F90, that validates correct compiler and runtime behavior for named constants used in OpenACC clauses

These tests ensure that:

Named constants are accepted syntactically in both compute and data clauses
The constants value is correctly available on the device at runtime
Coverage includes:
--- Scalar and array named constants
--- INTEGER and REAL types
--- Compute (firstprivate) and data clause paths (copyin, create, present_or_copyin)
all named constants are used read-only, consistent with fortran semantics.
Test Coverage Summary
•T1-T2: firstprivate(PARAMETER)
verifies that scalar INTEGER and REAL named constants may appear in firstprivate clauses and are correctly initialized per device worker.
•T3: scalar named constant in copyin
Ensures named constants are treated as valid var items in data clause lists.
•T4: array named constant in firstprivate
Covers array descriptor handling in compute clauses.
•T5: array named constant in copyin
Covers array named constants in data clause lowering paths.
•T6: scalar named constant in create
Ensures named constants are accepted in data clause variants beyond copyin, and that their values are usable on the device.
•T7: scalar named constant in present_or_copyin
Extends data-clause coverage to combined/conditional data clauses, ensuring named constants are accepted and correctly usable on the device even when data presence is conditional.

–correctness is validated by device-sided computations that depend on the named constant and host-side verification results.

Compiler Results:
NVC: 25.5.0
--PASS

GCC: 15.2.0
--PASS(emits warnings about constants in clauses, but executes correctly)

CRAY: 18.0.0
--Fails at compile time (rejects named constants in clauses; behavior is non-conforming with OpenACC 3.4)