Fixes #33197 - Show error message if credentials are wrong

Fixes #33033 - shell_escape template macro

New template macro `shell_escape` using
Ruby's `Shellwords.shellescape` for safe shell strings.

Use `shell_escape` for user input variables
in registration templates (`global` & `host_init`)

Fixes #33090 - load AIX OS attributes

Fixes #32540 - host_param_(true|false)? cleanup

let the `default_value` denote what we "read" by default from the host
(in the case the host doesn't have the param) and then compare it with
`true`/`false` (depending on the func) as done with the existing...

Fixes #31235 - drop Puppetclass models

Drops Puppetclass models and their usage.
Extracted in https://github.com/theforeman/foreman_puppet_enc/pull/81
Tests extracted in:
- hostgroup - https://github.com/theforeman/foreman_puppet_enc/pull/85

Fixes #32918 - Host registration - Update packages

New parameter `update_packages` for update of
all packages on the host when registered

Fixes #32635 - fix already initialized constant

Fixes #28221 - Adding passing of template scope for snippet rendering

In current implementation templates can be much complex by snippet.
Reusable pieces of template code that should be in the same scope like
their templates but they are not. This PR tries to solve that.

Fixes #32192 - Override only the relevant parts

Fixes #32192 - Monkey patch restclient to unescape proxy credentials

Restclient as of version 2.1.0 uses provided credentials stored in a proxy URI
object verbatim. If the credentials are escaped as they should be, then this
leads to errors when we try to use the credentials because restclient sends the...