Fix array declarations in IDL serialization

[vpfkfl753]

Description

idl_serialize() writes array bounds before the name in typedefs and union members, for example typedef double[9] Covariance;. Reuse the struct-member declaration formatting so the bounds follow the name.

The regression tests cover one- and multidimensional arrays, chained aliases, and labelled/default union members. The alias test also parses the emitted IDL and compares the resulting type.

Tested on Ubuntu 24.04 with GCC 13.3, Debug: both new tests fail before the fix; all 16 IDL serialization tests pass after it. Uncrustify passes. Local line coverage of dynamic_type_idl.cpp increases from 480/590 (81.36%) to 488/599 (81.47%). The linked nightly coverage server timed out, so this comparison uses the local baseline.

Backport: 3.6.x has the same serializer; the patch applies cleanly there.

Fixes #6509.

Contributor Checklist

• Commit messages follow the project guidelines.
• The code follows the style guidelines of this project.
• Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally
• Any new/modified methods have been properly documented using Doxygen.
• N/A Any new configuration API has an equivalent XML API (with the corresponding XSD extension) No configuration API changes.
• Changes are backport compatible: they do NOT break ABI nor change library core behavior.
• Changes are API compatible.
• N/A New feature has been added to the versions.md file (if applicable). Bug fix; no new feature.
• N/A New feature has been documented/Current behavior is correctly described in the documentation. Restores valid IDL output; no documentation change.
• Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• The title and description correctly express the PR's purpose.
• Check contributor checklist is correct.
• If this is a critical bug fix, backports to the critical-only supported branches have been requested.
• Check CI results: changes do not issue any warning.
• Check CI results: failing tests are unrelated with the changes.