### Summary
#1667 updated several Unstructured loaders to accept
`unstructured_kwargs` in the `__init__` function. However, the previous
PR did not add this functionality to every Unstructured loader. This PR
ensures `unstructured_kwargs` are passed in all remaining Unstructured
loaders.
### Summary
Adds support for MSFT Outlook emails saved in `.msg` format to
`UnstructuredEmailLoader`. Works if the user has `unstructured>=0.5.8`
installed.
### Testing
The following tests use the example files under `example-docs` in the
Unstructured repo.
```python
from langchain.document_loaders import UnstructuredEmailLoader
loader = UnstructuredEmailLoader("fake-email.eml")
loader.load()
loader = UnstructuredEmailLoader("fake-email.msg")
loader.load()
```
Matt Robinson