roles/git: ssh known_hosts is now idempotent

- roles/git now uses blockinfile to ensure the github ssh keypairs are trusted, and to allow subsequent ssh keypairs to be trusted and not overwritten by future runs.
- this commit marks idempotency for all roles. after a successful run of this playbook, subsequent runs will result in a change=0 !!!!!

roles/gitea/tasks/main.yml

@@ -2,7 +2,7 @@
 - name: Check if Gitea is installed
   shell: gitea --version
   register: validate_gitea
-  changed_when: false
+  changed_when: no
 
 - name: Add Gitea key && repository
   block: