PCI: Add Recommendations Block to sidebar

Is your feature request related to a problem?

One of the big needs customers have when preparing a post for publication is making sure it connects to related content on their site(s). We are helping with this problem by offering smart links to embed throughout the body of the draft post, and related posts to surface related posts according to certain metas (author, tag, section).

What's missing? The option to quickly add a recommendations block to an article that uses ML to show other content, based on reader behavior + business goals, to improve recirculation through a site.

This is an existing feature available to certain customers in the block editor, but it is not readily apparent unless you know that block exists and are typing in the editor.

Let's make it visible and accessible directly in the PCI sidebar!

Describe the solution you'd like

Add a section to the PCI sidebar for Parse.ly Recommendations.
The section should include a quick description of what the block does, link to related documentation (i think we'll need to update what we have) and all the same functionality available in the block editor but in the sidebar.

Describe alternatives you've considered

The alternative is keeping the Recs Block as is and not surfacing it within the PCI sidebar.

Start by inspecting the existing Parse.ly Recommendations block in the block editor and the PCI sidebar entry point. Compare the block's current functionality with the requested sidebar section, including its description and related documentation link. Done means the sidebar makes Recommendations visible and provides the same functionality as the existing block.