OpenSystemsDevelopment / qpdf

By-pass an issue calling QPDFJob::createQPDF from pikepdf. See https://github.com/pdfarranger/pdfarranger/issues/1312

Reminder in release instructions to mention signer

Refactor QPDFParser

Co-authored-by: m-holger <34626170+m-holger@users.noreply.github.com>

Co-authored-by: m-holger <34626170+m-holger@users.noreply.github.com>

Co-authored-by: m-holger <34626170+m-holger@users.noreply.github.com>

Co-authored-by: m-holger <34626170+m-holger@users.noreply.github.com>

Bump version to 12.3.1

Fix Filename Masks in README-what-to-download.md

Fixes #1648

Minor fixes to release instructions

Allow README change to trigger CI (for 12.3.0)

Virtually all changes are merged through PRs now. The exclusions would
prevent a README change from being the last commit before a release.

Update README for C++20 requirement

Add script to validate private header files in isolation

Introduce `check-private-headers` script to ensure all private headers compile independently. Update `build-linux` script to include this new validation step. Adjust release notes to reflect the additional header checks.

Addresses the issue raised in #1465

Add `--remove-acroform` option to exclude AcroForm dictionary

Introduce a new `--remove-acroform` option to remove the interactive form dictionary from the document catalog. Update related documentation, tests, and release notes to reflect this new feature.

Fixes #1403

Refactor `FormNode::setRadioButtonValue` (fixes #1449)

Fix identification of radio button widgets by relying on the absence of `Kids` arrays.
Fix the exclusion of RadioButtonFields with parents.

Fixes #1449

Update copyrights

Tighten named destination validation in `QPDFOutlineDocumentHelper::r…

…Dest`: instead of accepting any Dictionary require a `/D` entry.

Enhance `AcroForm::transformAnnotations` to update '/P' field

Fix `Lin::readHintStream`

Reorder `no_ci_stop_if` call to avoid
insertion of an invalid object into the object cache if the hint stream is invalid

Refactor FormNode::generateTextAppearance

…t resource handling in `generateTextAppearance`.

…ance`: copy stream data if shared references exceed threshold, ensuring safe updates.

…r replace the appearance stream content with the generated appearance.

…g: ensure checks for dictionary annotations, streamline appearance creation flow, and replace manual key access with methods.