Introduce a way to access all page_routes in User testing

[Mte90]

Ref: #4264
Ref: #4276

[falkoschindler]

@Mte90 What exactly do you mean with "all page_routes"?
There is the dictionary Client.page_routes which can already be accessed.

[Mte90]

I wasn't sure if Client imported in unit tests results those kind of information.
In that case can be closed.