Fixes #35088 - Remove GCE Compute resource code

All code related to GCE compute resource
is now in Foreman Google plugin

https://github.com/theforeman/foreman_google

Fixes #35035 - set VNC password length to 8 chars.

VNC passwords have a maximum length of 8 characters, Foreman uses 16.
Newer versions of libvirt enforce the 8 character limit.
Improve strength of generated passwords by increasing the character pool.

Fixes #34526 - Switch Rails version to 6.1

Changes overview:
- Set default Rails version to 6.1
- Required dynfow >= 1.6.5
- Cleanup deprecation warnings in config/as_deprecation_whitelist.yaml
- ActiveSupport::ParameterFilter instead of ActionDispatch::Http::ParameterFilter...

Fixes #34498 - added RHEL9 and CentOS9 Guest OSes

Fixes #34346 - support Openstack URI with paths

The Keystone URI is processed before we pass it's base form to the fog.
If Keystone is deployed under a sub-uri e.g. /identity like Devstack
does, the path is always ommited. This preserves the path.

Fixes #34499 - new h/w versions for vSphere 7.0 U2 & U3

Fixes #14854 - connection libvirt leak fixed

Fixes #32273 - VMWare compute failure ends up in ArgumentError (too few arguments)

Fixes #33197 - Show error message if credentials are wrong

Fixes #33155 - Drop Spice XPI support

This plugin is no longer maintained and relied on Xulrunner support in
Firefox. That means that with Firefox 60 or newer it's broken.