Parse API in docs

[evvaaaa]

Currently, our api has nothing other than version:

https://diamondlightsource.github.io/FastCS/main/_api/fastcs.html

This is because our __init__.py doesn't actually expose the api in __all__:

FastCS/src/fastcs/__init__.py

Lines 1 to 13 in 5aa7a12

	"""Top level API.
	.. data:: __version__
	:type: str
	Version number as calculated by https://github.com/pypa/setuptools_scm
	"""
	from ._version import __version__
	from .launch import FastCS as FastCS
	from .launch import launch as launch
	__all__ = ["__version__"]

This means that downstream, when type hinting we get a sphinx warning:

.../Programming/fastcs-PandABlocks/src/fastcs_pandablocks/panda/blocks/__init__.py:docstring of fastcs_pandablocks.panda.blocks.block_controller.BlockController:1: WARNING: py:class reference target not found: fastcs.datatypes.DataType [ref.class]

and the type hint doesn't link in the API:

[GDYendell]

I fixed this in pvi by swapping to autodoc2. @coretl do you still think we should adopt this in the template?

[coretl]

I'm concerned with the lack of activity:

So I don't think I'll recommend it in the copier template, but we could always put it in FastCS