BED-8065: Add support to generate plain-markdown pages for other documentation engines

[d3vzer0]

Description

The current docs generation command relies on mkdocstrings' specific functions to render pages. For example, to render the docstrings you would simply refer to the Python (data)class inside a markdown file like so:

::: openhound_okta.source.source
    options:
        show_source_link: true
        show_root_heading: true
        heading_level: 3

In order to add support for mintlify (and other doc frameworks), this PR adds a new method to generate plain markdown files for all node and edge specific pages. This allows us to keep all the detailed docs in this repo, but at the same time generate node/edge descriptions that can be synced with the official bloodhound.specterops.io website.

Motivation and Context

We want to keep the documentation about nodes/edges for each collector up to date on the bloodhound.specterops.io website.

How Has This Been Tested?

• The test_docs_pipeline.py test generates collector docs and verifies if node and edge pages for the dummy collector are rendered in markdown correctly

Screenshots (if appropriate):

Types of changes

• Chore (a change that does not modify the application functionality)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)