Allow override of the repo filename

Apt cannot have 2 mirrors with the same content in 2 different files.
If a deployer has an apt mirror with uca, the deployer
still need to add a repository, but will also need to define the
filename used, in order to avoid clashes.

This commit makes possible to decide the filename for the repo.

Change-Id: I0302b9aea379b9b1974b4479bf85d45d1a052f65

releasenotes/notes/apt-source-filenamed-e710006ed93a9c67.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - The filename of the apt source for the ubuntu
+    cloud archive can now be defined with the
+    variable ``uca_apt_source_list_filename``.

tasks/nova_compute_powervm_install.yml

@@ -29,6 +29,7 @@
   apt_repository:
     repo: "{{ novalink_repo.repo }}"
     state: "{{ novalink_repo.state }}"
+    filename:  "{{ novalink_repo.filename | default(omit) }}"
     update_cache: yes
   register: add_nv_repos
   until: add_nv_repos|success

tasks/nova_install.yml

@@ -36,6 +36,7 @@
     repo: "{{ uca_repo }}"
     state: present
     update_cache: yes
+    filename: "{{ uca_apt_source_list_filename | default(omit) }}"
   register: nova_uca_add_repo
   when:
     - nova_uca_enable

vars/ubuntu-16.04.yml

@@ -74,6 +74,7 @@ nova_compute_lxd_distro_packages:
 uca_openstack_release: newton
 uca_repo_dist: "{{ ansible_lsb.codename }}-updates/{{ uca_openstack_release }}"
 uca_repo: "deb {{ uca_apt_repo_url }} {{ uca_repo_dist }} main"
+#uca_apt_source_list_filename: "ubuntu_cloud_archive_canonical_com_ubuntu"
 
 # nova powervm virt driver
 nova_compute_powervm_distro_packages:
@@ -93,6 +94,7 @@ nova_compute_powervm_distro_packages:
 novalink_repo:
   repo: "deb [arch=ppc64el] http://public.dhe.ibm.com/systems/virtualization/Novalink/debian/ novalink_1.0.0 non-free"
   state: "present"
+  filename: "public_dhe_ibm_com_systems_virtualization_Novalink_debian"
 
 novalink_gpg_keys:
   - url: "http://public.dhe.ibm.com/systems/virtualization/Novalink/debian/novalink-gpg-pub.key"