Allow for filepointers

[navarone-feekery]

Related to https://github.com/elastic/enterprise-search-team/issues/5137

Allow for filepointers on the /extract_text endpoint. If the request contains the parameter local_file_path it will be converted to the required headers for tika to access the file. local_file_path must be the full path of the file, which is inside docker.

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Related Pull Requests

https://github.com/elastic/connectors-python/pull/1219

[navarone-feekery]

@seanstory I added your change requests, but because they were nits and you approved I will merge for now. If there's anything else you think should be changed, let me know and I will do a follow-up PR.