feat(barcodes): add support for data matrix (2d) barcodes

[Chaz6]

Linked issue

#1183

What and why

Data Matrix barcodes are a common form of 2d barcode and the library currently lacks support for them.

Type of change

• Bug fix
• New feature (has an accepted issue: [Feature]: Generate Data Matrix (2d) barcodes #1183 )
• Performance
• Refactor / internal
• Docs / CI / chore
• Breaking change

Tests

• I added a test that fails before this change and passes after
  (revert-checked). For bug fixes the reproducer is a minimal synthetic
  PDF built in code — no third-party/reporter PDF is committed.
• Test named by defect class, not an issue/PR number; no
  contributor/company names in code or fixtures.
• cargo test passes, and the affected feature tiers:
  rendering / fips,icc / ml / binding (list which): ____
• cargo fmt --check and cargo clippy -- -D warnings are clean.

Regression on real PDFs

N/A

Diff summary vs main: 36 files changed, 979 insertions(+), 56 deletions(-)

Diff summary vs latest release:

AI assistance disclosure

• AI assistance: none
• I understand and can explain every line; the description and my review
  replies are written by me, not generated. This PR is not fully or
  predominantly AI-generated.

Checklist

• One logical change (no bundled refactor/perf/correctness).
• Commits follow Conventional Commits and are DCO signed-off (git commit -s).
• Docs/CHANGELOG.md updated if user-facing; reporters credited in the
  CHANGELOG (not in code).
• Public-API changes considered for semver (semver-checks will run).

[github-actions]

All contributors have signed the CLA ✍️ ✅
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[Chaz6]

I have read the CLA Document and I hereby sign the CLA