OpenSystemsDevelopment / qpdf

Removed the unnecessary `filterable` variable and streamlined the logic for handling stream decoding parameters. These changes eliminate redundant checks, improve readability, and ensure clarity in flow control for filter processing.

Replaced manual array handling with cleaner iteration using `as_array`. This improves code readability and ensures more robust processing of stream filter arrays.

Simplify and reorganize parsing logic to replace explicit filter name collection with direct filter creation. Added validation for unsupported filters, ensuring filters are cleared and errors returned when necessary. This improves code clarity and robustness.

Moved stream filter factory logic into `Members::filter_factory` for better encapsulation and maintainability. Removed redundant static filter factory map and improved error handling for invalid stream filter configurations.

Moved `expand_filter_name` calls to maintain uniformity and avoid redundant processing in filter handling. This ensures cleaner and more structured code without changing functionality.

Moved the filter abbreviation expansion logic from a static map to a new `expand_filter_name` method in `QPDF_Stream::Members`. This simplifies the code, improves maintainability, and consolidates the logic for easier testing and updates.

Only top-level XMP metadata is supposed to be left unencrypted. All
other metadata is not treated specially.

Move all stream-specific methods to new class qpdf::Stream

This improves indentation of long strings. This commit also fixes some
trailing whitespace in ChangeLog.

This reverts commit ff2a78f579ebdd06b417e34260a17dba06e71137, reversing
changes made to 8f54319f7a6514110f4b05cbbf1cb1c9fc8cb6a0.

1. Make class final
2. Pass og parameter by value
3. Properly initialize qpdf and og

Also, tweak QPDF::replaceObject to allow stream replacement without
violating the requirement that streams must always be indirect objects.

Also, remove QPDF::reserveStream as it does not do what the name implies
and having this as a separate methods does not aid code readability.

(Replacing the temporary implementation from the last commit.)

writeStreamJSON is a temporary implementation minimally adapted from
getStreamJSON.

Create an alternative to getJSON to allow an object handle to be written as JSON without the overhead of creating a JSON object.

Also, name the type QPDFValue::Description.

Remove parameters and return the description.

Set parsed offset at the same time as setting description.

Add optional parameter shallow. Change logic errors to runtime errors.

QPDFValueProxy wasn't a good name for it. We decided the evil of
having the header file be named QPDFObject_private.hh was less than
the evil of having the class be named something other than what it
should have been named.