build(docs)!: incorporate Ulwazi 1.0

[jahn-junior]

Bring in Ulwazi as the default theme for Sphinx Stack 3.0 and higher. Marking as breaking because this introduces new potential failure points for documentation projects.

• Removes custom templates that are now incompatible
• Remove unused html_title declaration
• Append " documentation" to project, as it's no longer visible in the banner or above the global nav
• Drops explicit notfound dependency, as it's now set up by Ulwazi
• Adds myst-parser to extensions, as it's no longer set up by canonical-sphinx

Note for reviewers: You'll have to check out and build locally to validate the changes. I'm mainly looking for feedback on the default configuration of the banner (link text, destination URLs, and so on).

---

• Have you updated CHANGELOG.md?
• Have you updated the documentation to reflect your changes?

[izmalk]

There is no Preview PR build here, which is weird. It would be helpful to test a few RTD-specific features, like Feedback links.

[jahn-junior]

@izmalk

There is no Preview PR build here, which is weird. It would be helpful to test a few RTD-specific features, like Feedback links.

It's because the RTD project is sourced from the sphinx-stack-docs repo. I'll create a new RTD project for testing changes here when I have some downtime. For these changes, I'd ask that you validate what you can without it, and we can ensure everything works when I update the docs repo to 3.0 (hopefully later today if I can get this merged).

[izmalk]

I'd ask that you validate what you can without it

Yes, I'm working on it.
So far everything seems to be mostly OK. There is a MyST extensions fix that I'm implementing into Ulwazi.
Other than that, a few minor things, including some stale comments in conf.py

[izmalk]

LGTM