Feat. Postprocessing control - custom page separator, postprocess function etc

[pradhyumna85]

To accommodate and resolve #37

Changes

Note: This PR adds changes on top of PR #39. If merged, this will accommodate changes of PR #39, which won't require the previous PR to be merged.

• added post_process_function param to override/skip Zerox's default format_markdown post processing on the model's text output.
• removed output_dir param and added output_file_path which is more flexible for arbitrary file extensions
• page_separator param added (used when writing the consolidated output to the output_file_path
• +Added way to skip validation of model's vision capability as model might not be added to the litellm static json config which has a list of models and their capabilities. https://github.com/BerriAI/litellm/blob/main/model_prices_and_context_window.json

Edit:
Fixes #42

[tylermaran]

I'll take a look and test this one as well. I like the page_separator optional param. I was thinking of adding a <=== Page {x} ===> to our own use of zerox the other day. So make sense!

[pradhyumna85]

I'll take a look and test this one as well. I like the page_separator optional param. I was thinking of adding a <=== Page {x} ===> to our own use of zerox the other day. So make sense!

@tylermaran, you want to provide an option to pass a string with fixed placeholder like {page_no} (if this placeholder is not found then we don't populate anything) and populate that with the page number while writing the output markdown file (if the user has choosed to output)?

[tylermaran]

Hey @pradhyumna85, thinking through this a bit more. Right now we return an array of objects (including page number, content, etc.). So for our day to day use I was doing:

const result = await zerox(...)
const aggregatedText = result.pages.map((el) => el.content).join('\n\n');

But if we're writing to the output directory, it makes sense to have a configurable page deliminator built in. Although something like === Page {X} === might be a better default than \n\n.

[pradhyumna85]

@tylermaran, Added the functionality for you to have a look.

[pradhyumna85]

@tylermaran could you review this PR for merging.

Also should I incorporate the new system prompt from #48?