DM-15777: Directive that summarizes a Task's Python API

[jonathansick]

This PR adds a directive that generates a summary of the Python API for a task class. This is meant to be used in task topic pages to bridge task documentation to the autodoc-generated API reference documentation for the task class.

Usage:

Python API summary
==================

.. lsst-task-api-summary:: lsst.pipe.tasks.assembleCoadd.AssembleCoaddTask

[jonathansick]

Example showing the API summary where classes and methods are linked to the API docs. The summary for each is also shown. The user is expected to follow the link to get the full parameters and returns etc documentation.

The code block is an affordance that shows where the task is located in the package namespace, and is also copy-and-pastable.

[jonathansick]

Now with an addendum linking to the full API docs. Hopefully this will reinforce the bridge between the task topic and the API topic.

[jonathansick]

Some additional affordances:

• each signature has a type for clarity
• The linked "..." reinforces the bridge to the API docs.

[jonathansick]

Now including the config attribute and wrapping the addendum link in a seealso admonition node:

[jonathansick]

Cleaned up the ellipsis links by make it a more natural extension of the API summary sentence.