[FR] Add FTUE

[matmair]

Problem
We currently just drop the user in - some kind of out-of-the-box or first-time-user widget could be a good way to familiarize the user with the interface.

Suggested solution
Add a FTUE with:

• multi-step-wizards
• state saving per user
• short introduction
• link to the docs
• link to the blog (coming soo (tm))
• a way for plugins to provide pages

Describe alternatives you've considered
The current way works. For 1.0.0 maybe a basic setup would be nice

Examples of other systems
Nextcloud has a nice, 3 step FTUE - there are fuller examples in closed source systems but I am not sure if I am able to share infos about that.

Do you want to develop this?
Yes - When the time is ready

[SchrodingersGat]

Yeah, this would be a major step forward in terms of user friendliness. 100% on board

[matmair]

This will be a lot about user-friendliness - this does not need to be a core-dev activity once the code for #2284 and the first few tasks are done.

[matmair]

Waiting for #3901

[SchrodingersGat]

wiki.js is an example of a good first-time-admin-experience