Add more demo data & features

[thibaudcolas]

Solves part of #175, particularly things we’d want to have for demos & audits or common features. This might be easier to review com

• Promoted search results. Includes a basic implementation of the feature, and demo data.
• Demo users, to simplify switching between languages and groups, as well as checking what an inactive user looks like
• Demo redirects, based on real examples from the project (as part of renaming pages where the slug was incorrect, and demonstrating common typos)
• Wagtail’s dynamic image serve view. Bit of a niche feature but useful to be able to demo it when needed
• Focal points

Compared to #175, still missing are pages in different states, revisions, and documents

[Stormheg]

I'm happy with this!

I've added a section to the readme documenting the different users. Does this look okay to you @thibaudcolas?

Feel free to merge.

[thibaudcolas]

Thank you @Stormheg @laymonage! I switched the users’ documentation to a table so it’s simpler to compare the available options at a glance. Our new users are:

• Eddy Thorsørensen
• Jordan Rules
• Iman Absent
• Friedrich Wilhelm von Braunenberg
• Nour al-Hudā

I tried to add examples that were somewhat representative for German from Germany and Arabic from Lebanon speakers, with a mixture of lengths, and diacritics / non-latin characters.

[laymonage]

OMG, Eddy Thor(sørensen) is now canon!