add static facility and apply to register (#49737)

* add static facility and apply to register

* added warning

* added test for templated register

* test register 'static' status

* rely on subshell to deal with quote context

* use corrects pb for test

* bring constants back cause new code in devel

test/integration/targets/templating_settings/dont_warn_register.yml

@@ -0,0 +1,6 @@
+- hosts: testhost
+  gather_facts: false
+  tasks:
+    - name: template in register warns, but no template should not
+      debug: msg=unimportant
+      register: thisshouldnotwarn

test/integration/targets/templating_settings/runme.sh

@@ -3,3 +3,5 @@
 set -eux
 
 ansible-playbook test_templating_settings.yml -i ../../inventory -v "$@"
+ansible-playbook warn_on_register.yml -i ../../inventory -v "$@" 2>&1| grep 'is not templatable, but we found'
+[ "$(ansible-playbook dont_warn_register.yml -i ../../inventory -v "$@" 2>&1| grep -c 'is not templatable, but we found')" == "0" ]

test/integration/targets/templating_settings/warn_on_register.yml

@@ -0,0 +1,8 @@
+- hosts: testhost
+  gather_facts: false
+  vars:
+    thisshouldwarn: noreally
+  tasks:
+    - name: template in register warns
+      debug: msg=unimportant
+      register: '{{ thisshouldwarn }}'