Description of problem:
In BZ#1813986 it was reported, that passing "size_gb: <an array>" of volumes_attributes to the compute_resources API will lead to an ISE, and it was fixed by checking that all parameters in "volumes_attributes" are strings (see https://github.com/theforeman/foreman/pull/7873).

This breaks perfectly valid requests that pass "size_gb: 50" (so an Integer) instead of "size_gb: '50'".

Additionally, the request was for a "Meaningful error message, like "Incorrect value of argument 'size_gb'"", but the current implementation just throws "VM volume attributes are not set properly" which neither indicates *which* volume attribute is wrong, neither *what* is wrong about it.

I would consider this a (albeit small) regression in Satellite 6.9 (as this is the first version shipping this code change).

Version-Release number of selected component (if applicable):
Satellite 6.9.7 (but really, anything that's based on Foreman 2.3 or newer)

How reproducible:
100%

Steps to Reproduce:
1. run the following Ansible playbook:
---
- hosts: localhost
  tasks:
    - name: Create compute profiles
      redhat.satellite.compute_profile:
        username: "admin"
        password: "changeme"
        server_url: https://satellite.example.com
        name: test
        compute_attributes:
        - compute_resource: rhevm1
          vm_attrs:
            volumes_attributes:
              0:
                size_gb: 50


Actual results:
fatal: [satellite.example.com]: FAILED! => changed=false 
  error:
    message: 'ERF42-2471 [Foreman::Exception]: VM volume attributes are not set properly'
  msg: 'Error while performing create on compute_attributes: 500 Server Error: Internal Server Error'

Expected results:
It to work.
Or at least give a hint what's wrong.

Additional info:
- I think the API should accept both, Strings and Integers (and probably Booleans?), and only throw an error for *other* types. And then the error should say *which* entry is wrong and what it should look like to be valid.
- In a perfect world, this would be expressed an an Apipie validation in the APIdoc, but I think we don't document possible volumes_attributes at all in the apidoc :(