Update partition_eml and partition_msg to capture cc, bcc, and message
id fields.
Docs PR: https://github.com/Unstructured-IO/docs/pull/135/files
Testing
```
from unstructured.partition.email import partition_email
from test_unstructured.unit_utils import example_doc_path
elements = partition_email(filename=example_doc_path("eml/fake-email-header.eml"), include_headers=True)
print(elements)
elements[0].metadata.to_dict()
```
Note to reviewers:
Tests in `test_unstructured/partition/test_email.py` were refactored and
rearranged to group similar tests together, so it will be easiest to
review those changes commit by commit.
---------
Co-authored-by: ryannikolaidis <1208590+ryannikolaidis@users.noreply.github.com>
Co-authored-by: Coniferish <Coniferish@users.noreply.github.com>
* Adds functionality to extract charset info from eml files
* Adds missed file-like object handling in detect_file_encoding
* Adds functionality to replace the MIME encodings for eml files with one of the
common encodings if a unicode error occurs
* Organize the eml example files in the example-docs/eml directory
