feat: added http header support for document converter and cli (#642)

* added http header support for document converter and cli

Signed-off-by: Luke Harrison <Luke.Harrison1@ibm.com>

* fixed formatting and typing issues

Signed-off-by: Luke Harrison <Luke.Harrison1@ibm.com>

* use pydantic to parse dict

suggested by @dolfim-ibm

Co-authored-by: Michele Dolfi <97102151+dolfim-ibm@users.noreply.github.com>
Signed-off-by: Luke Harrison <luke.harrison1@ibm.com>

---------

Signed-off-by: Luke Harrison <Luke.Harrison1@ibm.com>
Signed-off-by: Luke Harrison <luke.harrison1@ibm.com>
Co-authored-by: Michele Dolfi <97102151+dolfim-ibm@users.noreply.github.com>

docling/datamodel/document.py

@@ -227,13 +227,18 @@ class _DummyBackend(AbstractDocumentBackend):
 class _DocumentConversionInput(BaseModel):
 
     path_or_stream_iterator: Iterable[Union[Path, str, DocumentStream]]
+    headers: Optional[Dict[str, str]] = None
     limits: Optional[DocumentLimits] = DocumentLimits()
 
     def docs(
         self, format_options: Dict[InputFormat, "FormatOption"]
     ) -> Iterable[InputDocument]:
         for item in self.path_or_stream_iterator:
-            obj = resolve_source_to_stream(item) if isinstance(item, str) else item
+            obj = (
+                resolve_source_to_stream(item, self.headers)
+                if isinstance(item, str)
+                else item
+            )
             format = self._guess_format(obj)
             backend: Type[AbstractDocumentBackend]
             if format not in format_options.keys():