[CT-1252] [Feature] Create GHA to autogenerate documentation using Sphinx

[leahwicz]

Describe the feature

This is the next step after this ticket #5528

After we have Sphinx configured and able to generate documentation for our future APIs, we want to be able to automate this by using GitHub Actions.

Exit criteria: a GitHub Action that-

• you can trigger manually or on a push to main or release branches
• the documentation is uploaded as an artifact of the run

Future work out of scope for this:

• Uploading docs to during to our GitHub Release automatically
• Leveraging these docs in the docs website