DCD-224: Refactor some names and add postgresql from extras.

roles/aws_linux2_product_common/tasks/main.yml

@@ -0,0 +1,12 @@
+---
+
+# Amazon Linux 2 supplies extra packages via a special command.
+- name: Enable Postgresql from 'extras'
+  command: amazon-linux-extras enable -y "postgresql{{ postgres_version }}"
+
+- name: Install Java and other base packages
+  yum:
+    name:
+      - java-{{java_version}}-openjdk-devel
+      - git-{{git_version}}
+      - postgresql