feat: Make Page.parsed_page the only source of truth for text cells, add OCR cells to it (#1745)

* Keep page.parsed_page.textline_cells and page.cells in sync, including OCR

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

* Make page.parsed_page the only source of truth for text cells

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

* Small fix

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

* Correctly compute PDF boxes from pymupdf

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

* Use different OCR engine order

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

* Add type hints and fix mypy

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

* One more test fix

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

* Remove with pypdfium2_lock from caller sites

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

* Fix typing

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

---------

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

tests/test_e2e_ocr_conversion.py

@@ -57,14 +57,14 @@ def test_e2e_conversions():
     pdf_paths = get_pdf_paths()
 
     engines: List[Tuple[OcrOptions, bool]] = [
-        (EasyOcrOptions(), False),
         (TesseractOcrOptions(), True),
         (TesseractCliOcrOptions(), True),
-        (EasyOcrOptions(force_full_page_ocr=True), False),
+        (EasyOcrOptions(), False),
         (TesseractOcrOptions(force_full_page_ocr=True), True),
         (TesseractOcrOptions(force_full_page_ocr=True, lang=["auto"]), True),
         (TesseractCliOcrOptions(force_full_page_ocr=True), True),
         (TesseractCliOcrOptions(force_full_page_ocr=True, lang=["auto"]), True),
+        (EasyOcrOptions(force_full_page_ocr=True), False),
     ]
 
     # rapidocr is only available for Python >=3.6,<3.13