feat: Introduce docling-parse v5 and deprecate old docling-parse backends (#2872)

* feat: simplifying towards docling-parse v5

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* working on integrating docling-parse v5

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* added the test_backend_docling_parse

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* Updated the docling-parse to 5.3.0

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* ran the pre-commit

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* fixed the backend_docling_parse

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* ran pre-commit

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* updated the groundtruth to deal with rounding errors

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* updated comments for later docling-parse integrations

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* ran pre-commit

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

* Make DoclingParseV2 and DoclingParseV4 backend stubs that route to new backend, emit warning.

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

* lock docling-parse

Signed-off-by: Michele Dolfi <dol@zurich.ibm.com>

* updated to 3.5.2

Signed-off-by: Peter Staar <taa@zurich.ibm.com>

---------

Signed-off-by: Peter Staar <taa@zurich.ibm.com>
Signed-off-by: Christoph Auer <cau@zurich.ibm.com>
Signed-off-by: Michele Dolfi <dol@zurich.ibm.com>
Co-authored-by: Christoph Auer <cau@zurich.ibm.com>
Co-authored-by: Michele Dolfi <dol@zurich.ibm.com>