feat: moved network to separate template, additional packages loop, fixed qemu-guest-agent install

builds/linux/ubuntu/20-04-lts/data/user-data.pkrtpl.hcl

@@ -9,12 +9,11 @@ autoinstall:
         uri: http://archive.ubuntu.com/ubuntu
       - arches: [default]
         uri: http://ports.ubuntu.com/ubuntu-ports
-  early-commands:
-    - sudo systemctl stop ssh
   locale: ${vm_os_language}
   keyboard:
     layout: ${vm_os_keyboard}
 ${storage}
+${network}
   identity:
     hostname: ubuntu-server
     username: ${build_username}
@@ -24,8 +23,10 @@ ${storage}
     allow-pw: true
   packages:
     - openssh-server
-    - qemu-guest-agent
     - cloud-init
+%{ for package in additional_packages ~}
+    - ${package}
+%{ endfor ~}
   user-data:
     disable_root: false
     timezone: ${vm_os_timezone}
@@ -33,3 +34,5 @@ ${storage}
     - sed -i -e 's/^#\?PasswordAuthentication.*/PasswordAuthentication yes/g' /target/etc/ssh/sshd_config
     - echo '${build_username} ALL=(ALL) NOPASSWD:ALL' > /target/etc/sudoers.d/${build_username}
     - curtin in-target --target=/target -- chmod 440 /etc/sudoers.d/${build_username}
+    - curtin in-target -- apt-get update
+    - curtin in-target -- apt-get install qemu-guest-agent