DCD-224: Rename product_download to tgz_download in prep for an alternative installer.

roles/tgz_download/tasks/main.yml

@@ -0,0 +1,13 @@
+---
+
+# Common case for most products and Jira editions.
+- name: Fetch ServiceDesk metadata if necessary
+  include_tasks: "servicedesk_download.yml"
+  when: atl_product_edition == "jira-servicedesk"
+
+# Differences for ServiceDesk become fiddly enough that it's better to
+# just split them out and move common functionality into individual
+# task files.
+- name: Fetch product metadata if necessary
+  include_tasks: "product_download.yml"
+  when: atl_product_edition != "jira-servicedesk"