Speed up testing, docs. Start exporting fixtures.

[tonyfast]

• begins a pytest axe extension and fixture
• adds xfailing tests for parts of the design
• adds docs and docs exports to ci
• removes old ci

cf https://iota-school.github.io/notebooks-for-all/branch/smoke-testing/exports/html/lorenz-executed-a11y.html

[github-actions]

A preview fo the exported examples will be rendered at
https://iota-school.github.io/notebooks-for-all/branch/smoke-testing/exports/html

[tonyfast]

this pull request introduces future work that needs to be done. each of the dialogs we have introduced are tested. some of them need more work to pass, and more complex test paths.