Function of_type for getting an instance for a given type name

[joente]

Description

For a single ID we have no direct function to load the instance for a dynamic type name.

If known, we can simple write:

t = T(123);

But when dynamic, we have to write something like this:

type_name = 'T';

// use map_type for dynamic type name
t = [123].map_type(type_name)[0];

// or using thing(..) + assert(..)
t = thing(123); 
assert(type(t) == type_name);

This PR introduces a dedicated function for this purpose for the int type:

(123).of_type(type_name);

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• Test collection functions

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• New and existing unit tests pass locally with my changes