Upcast named arguments/named parameters in views

Problem/Motivation

Upcasting of named arguments does not work.

Proposed resolution

Add proper parameter type hints to routes generated by views.

In order for the patch to work, the contextual filter of the same position of the named argument needs to have a simple validation of it being an entity of a specific type (if it's entity), only then the upcast will work.

Remaining tasks

User interface changes

API changes

Data model changes