unit test helper: big revamp (#8894)

* initial commit

* multiple changes:

- TestCaseContext fixture no longer need to autouse=True
- Helper.from_module() allows extra param to specify yaml file
- test_django_check: adjusted .py and .yaml

* set fixtures per testcase

* set fixtures per testcase

* rollback to original state

* patch_ansible_module fixture

- now it works not only in parametrized functions but also directly with args

* tests/unit/plugins/modules/helper.py

- improved encapsulation, class Helper no longer knows details about test cases
- test functions no longer parametrized, that allows using test case fixtures per test function
- renamed 'context' to 'mock'

* enable Helper.from_list(), better param name 'ansible_module'

* adjusted test fiels to new helper

* remove unnecessary .license file

* fix bracket

* fix reference name

* Update tests/unit/plugins/modules/helper.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* revert to parametrized test func instead of multiple funcs

---------

Co-authored-by: Felix Fontein <felix@fontein.de>

tests/unit/plugins/modules/test_gconftool2.yaml

@@ -13,7 +13,8 @@
   output:
     new_value: '200'
     changed: true
-  run_command_calls:
+  mocks:
+    run_command:
     - command: [/testbin/gconftool-2, --get, /desktop/gnome/background/picture_filename]
       environ: &env-def {environ_update: {LANGUAGE: C, LC_ALL: C}, check_rc: true}
       rc: 0
@@ -38,7 +39,8 @@
   output:
     new_value: '200'
     changed: false
-  run_command_calls:
+  mocks:
+    run_command:
     - command: [/testbin/gconftool-2, --get, /desktop/gnome/background/picture_filename]
       environ: *env-def
       rc: 0
@@ -63,7 +65,8 @@
   output:
     new_value: 'false'
     changed: false
-  run_command_calls:
+  mocks:
+    run_command:
     - command: [/testbin/gconftool-2, --get, /apps/gnome_settings_daemon/screensaver/start_screensaver]
       environ: *env-def
       rc: 0
@@ -84,9 +87,10 @@
     state: absent
     key: /desktop/gnome/background/picture_filename
   output:
-    new_value: null
+    new_value:
     changed: true
-  run_command_calls:
+  mocks:
+    run_command:
     - command: [/testbin/gconftool-2, --get, /desktop/gnome/background/picture_filename]
       environ: *env-def
       rc: 0
@@ -102,9 +106,10 @@
     state: absent
     key: /apps/gnome_settings_daemon/screensaver/start_screensaver
   output:
-    new_value: null
+    new_value:
     changed: false
-  run_command_calls:
+  mocks:
+    run_command:
     - command: [/testbin/gconftool-2, --get, /apps/gnome_settings_daemon/screensaver/start_screensaver]
       environ: *env-def
       rc: 0