Solution to issue
https://github.com/Unstructured-IO/unstructured/issues/2321.
simple_salesforce API allows for passing private key path or value. This
PR introduces this support for Ingest connector.
Salesforce parameter "private-key-file" has been renamed to
"private-key".
It can contain one of following:
- path to PEM encoded key file (as string)
- key contents (PEM encoded string)
If the provided value cannot be parsed as PEM encoded private key, then
the file existence is checked. This way private key contents are not
exposed to unnecessary underlying function calls.
