docs: sphinx, autodoc2, doctests setup

[aorumbayev]

Proposed Changes

• Adding docs using similar setup/theme as puya repos

[aorumbayev]

@joe-p a lot of docstrings are still not reST styled, for better rendering by sphinx please change those from google style to the rest.

The header of index.md file in docs demonstrates an example of a doctest (in that case the snippet for launching the library in quickstart has actual code that doctests execute as part of poetry run poe docs-test) - that way you can have extra confidence that each snippet in docs is a valid code ready to be copy pasted for use. Feel free to expand remaining snippets to be runnable chunks of python code as well.

[aorumbayev]

Would also suggest adding contributing MD and integrating semantic releases bot (for semantic releases bot specifically you can find many references on algokit cli, utils py, generator py, puya and puya unit testing repos)

[joe-p]

Amazing thanks @aorumbayev!