Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "Add pre-{install,purge} support for base image"
  - Add pre-{install,purge} support for base image

    Extend <lib.sh> and its invocation from <ci.deploy.sh> with
    support for modifying foundation node VMs base image prior to
    using it with:
    - additional APT GPG keys;
    - additional APT repos;
    - packages to pre-install;
    - packages to pre-remove;
    - (non-configurable) cloud init datasource via NoCloud only,
      so VCP VMs won't wait for metadata service;

    While at it, re-use the resulting image as a base for another
    round of pre-patching (same operations as above are supported)
    to provide a base image for VCP VMs.

    Add AArch64-specific configuration based on new mechanisms:
    - pre-install linux-image-generic-hwe-16.04-edge (and headers)
      for foundation node and VCP (common) image (also requires new
      repo and its key);
    - pre-install cloud-init for VCP image (it should already be
      installed, but script needs non-empty config for VCP to create
      the VCP image and transfer it over to Salt Master);

    NOTE: cloud-init is required on VCP VMs for DHCP on 1st iface.

    JIRA: FUEL-309

    Change-Id: I7dcaf0ffd9c57009133c6d339496ec831ab14375
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>