feat: plugin for generating a partial library when building a pod

[Zoramite]

Adds a hook for amagaki that triggers before the manifest is built (allowing the plugin to generate more content outside of normal routes and after all routes have been processed). This extra trigger allows for plugins that want to do analysis of normal builds to hook into the process and generate reports or files before deploying.

The partial library plugin is made to be used with a custom view in the project (allows the project to control how the partials are displayed and gives access to the information from the library). This allows the project to be able to include normal styling or framing around how the library information is displayed and supports the normal template engines based on the view provided.