Main changes

• Drop EDGE deployment options
• Drop LXD/LXC, Firecracker hypervisor deployments
• Only frontend + local KVM or plain fronted are supported - other hypervisors could be provision using new FireEdge

Other improvements or fixes

• Effectively disable SELinux across reboots
• Fix ssh-keygen passphrase
• Update libgcrypt on CentOS8
• Fix install terraform, ssh-keygen
• Fix updating VM template
• Fix uninstall on Debian
• Skip bridge-utils install on RH8
• Disable firewall also for frontend-only
• Switch tap0 iface to auto
• Fix Debian needs bridge-utils, install it always
• Make ipv4 forwarding persistent
• Install init-system-helpers on Debian
• Fix install network-scripts if missing on CentOS8
• other minor and typos fixes