Refactor openpdf-renderer to use openpdf-core as PDF parser

[andreasrosdal]

Replace the internal PDF parsing logic in openpdf-renderer with the existing, more mature PDF parser from openpdf-core.

https://github.com/LibrePDF/OpenPDF/tree/master/openpdf-core
https://github.com/LibrePDF/OpenPDF/tree/master/openpdf-renderer

https://github.com/LibrePDF/OpenPDF/blob/master/openpdf-renderer/src/main/java/org/openpdf/renderer/PDFFile.java

https://github.com/LibrePDF/OpenPDF/blob/master/openpdf-renderer/src/main/java/org/openpdf/renderer/PDFPage.java

https://github.com/LibrePDF/OpenPDF/blob/master/openpdf-renderer/src/main/java/org/openpdf/renderer/decode/PDFDecoder.java

https://github.com/LibrePDF/OpenPDF/blob/master/openpdf-renderer/src/main/java/org/openpdf/renderer/PDFParser.java

Key Benefits:
Consistency: Ensures identical PDF interpretation between the core library and the renderer.
Maintenance: Removes redundant code, allowing for centralized bug fixes and security patches.
Reliability: Leverages the battle-tested parsing engine within the core module.
Efficiency: Focuses rendering development strictly on Java2D/Swing integration rather than parsing logic.