Add image content extraction

### Problem Description

We currently only have Apache Tika as an extraction tool. This doesn't support image content extraction.

### Proposed Solution

If we implement [Tesseract OCR](https://github.com/tesseract-ocr/tesseract) (or something similar) we can add image content extraction to the extraction service.

### Alternatives

Other tools are also acceptable if we investigate first.

### Additional Context

This should be extractable from the same endpoint that Tika is extracted from `/extract_text`, but would require adding a param for extraction type so we can differentiate between Tika and the image extractor.
The response format should be identical.