Filter page types by tags on add new screen.

[frozzare]

Is your feature request related to a problem? Please describe.
When you have a lot of page types it can be kind of hard to find which you should choose.

Describe the solution you'd like
Tagging page types could be a good solution.

Describe alternatives you've considered
n/a

Additional context
n/a

Something like this:

[frozzare]

Made som backend and javascript work on this task in 553253c

To Do:

• clear selected tags (button or cross on selected tag)
• css!