OpenSystemsDevelopment / qpdf

- Introduced a `validate()` method in `QPDFNameTreeObjectHelper`, `QPDFNumberTreeObjectHelper`, and `NNTreeImpl`.
- Ensure proper validation of tree keys and values, detecting invalid entries, unsorted keys, and inconsistencies.
- Added support for auto-repair in case of validation errors.

- Introduced `std::function<bool(QPDFObjectHandle const&)>` to validate tree values.
- Updated constructors and methods across `QPDFNameTreeObjectHelper` and `QPDFNumberTreeObjectHelper` to support value validation.
- Refactored `NNTreeImpl` to check for invalid values during insertion, iteration, and retrieval.
- Improved error handling and reporting for invalid values.

… checking, and align with `Array` API conventions.

…prove bounds checking

…y, modify bounds checks, and adjust affected tests.

… to use subscript operators, and simplify object access logic.

…reamline object assignment, and introduce constructors for `QPDFObjectHandle`.

…eplace `getArrayNItems` with `size`, and improve error handling logic.

…lify `withinLimits` logic, and improve code readability with subscript operators.

…edundant debug traces.

…and improve `findInternal` readability.

…`, and simplify member access.

…mplify control flow, and update method returns.

Refactor array handling in `QPDFObjectHandle`: replace `int` with `size_t` for size and index operations, introduce utility functions for type conversions, and simplify sparse array logic.

… warnings, and centralize utility methods.

… numbers and related variables, replacing `int`, to enhance consistency and avoid unnecessary checked conversions.

…r,  and revise enum initialization. Clean up unused error handling in linearization logic.

…oding/decoding logic, and simplify usage in `JSON_writer` and `QPDF_json`.

…view` for encoding/decoding, improving memory efficiency and simplifying buffer management

…e` and `finish` logic

…dding error counting and leveraging `reconstructed_xref` for improved robustness, limiting the acceptable number of errors for damaged files.

…string`, improving performance, simplifying stream data handling, and reducing dependency on `BufferInputSource`.

…ancy and improving initialization consistency.

…ndant methods for improved code clarity.

…ng encapsulation and maintainability.

Replaced raw key pointer and length parameters with a `std::string` in `Pl_AES_PDF` and `Pl_RC4` constructors for improved safety and clarity. Updated all usage sites accordingly, reducing reliance on manual memory management and redundant conversions.

…proved clarity and reduced indirection in pipeline management.

…proved clarity and reduced indirection in pipeline management.

…te encryption handling

… overloads, streamline QDF handling, and simplify string and trailer writes.

…onsolidate `iterate_rc4` logic, and streamline RC4 key processing.

…arrays with `std::string`, and simplify key computation logic.

…nline previously separate method, and streamline data encoding logic.

…uce redundancy, improve maintainability, and streamline parameter handling.

…dom_string`, improve readability of salts and keys handling, and streamline `compute_Perms_value_V5_clear` logic by returning strings directly.