community[minor]: add support for llmsherpa (#19741)

Thank you for contributing to LangChain!

- [x] **PR title**: "community: added support for llmsherpa library"

- [x] **Add tests and docs**: 
1. Integration test:
'docs/docs/integrations/document_loaders/test_llmsherpa.py'.
2. an example notebook:
`docs/docs/integrations/document_loaders/llmsherpa.ipynb`.


- [x] **Lint and test**: Run `make format`, `make lint` and `make test`
from the root of the package(s) you've modified. See contribution
guidelines for more: https://python.langchain.com/docs/contributing/

Additional guidelines:
- Make sure optional dependencies are imported within a function.
- Please do not add dependencies to pyproject.toml files (even optional
ones) unless they are required for unit tests.
- Most PRs should not touch more than one package.
- Changes should be backwards compatible.
- If you are adding something to community, do not re-import it in
langchain.

If no one reviews your PR within a few days, please @-mention one of
baskaryan, efriis, eyurtsev, hwchase17.

---------

Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/tests/integration_tests/document_loaders/test_llmsherpa.py

@@ -0,0 +1,46 @@
+from langchain_community.document_loaders.llmsherpa import LLMSherpaFileLoader
+
+file_path = "https://arxiv.org/pdf/2402.14207.pdf"
+
+
+def test_llmsherpa_file_loader_initialization() -> None:
+    loader = LLMSherpaFileLoader(
+        file_path=file_path,
+    )
+    docs = loader.load()
+    assert isinstance(loader, LLMSherpaFileLoader)
+    assert hasattr(docs, "__iter__")
+    assert loader.strategy == "chunks"
+    assert (
+        loader.url
+        == "https://readers.llmsherpa.com/api/document/developer/parseDocument?renderFormat=all&useNewIndentParser=true&applyOcr=yes"
+    )
+    assert len(docs) > 1
+
+
+def test_apply_ocr() -> None:
+    loader = LLMSherpaFileLoader(
+        file_path=file_path,
+        apply_ocr=True,
+        new_indent_parser=False,
+    )
+    docs = loader.load()
+    assert (
+        loader.url
+        == "https://readers.llmsherpa.com/api/document/developer/parseDocument?renderFormat=all&applyOcr=yes"
+    )
+    assert len(docs) > 1
+
+
+def test_new_indent_parser() -> None:
+    loader = LLMSherpaFileLoader(
+        file_path=file_path,
+        apply_ocr=False,
+        new_indent_parser=True,
+    )
+    docs = loader.load()
+    assert (
+        loader.url
+        == "https://readers.llmsherpa.com/api/document/developer/parseDocument?renderFormat=all&useNewIndentParser=true"
+    )
+    assert len(docs) > 1