coverage for lookup_config (#68566)

Signed-off-by: Rick Elrod <rick@elrod.me>

test/integration/targets/lookup_config/aliases

@@ -0,0 +1,3 @@
+shippable/posix/group2
+skip/aix
+skip/python2.6  # lookups are controller only, and we no longer support Python 2.6 on the controller

test/integration/targets/lookup_config/tasks/main.yml

@@ -0,0 +1,59 @@
+- name: Verify lookup_config errors with no on_missing (failure expected)
+  set_fact:
+    foo: '{{lookup("config", "THIS_DOES_NOT_EXIST")}}'
+  ignore_errors: yes
+  register: lookup_config_1
+
+- name: Verify lookup_config errors with on_missing=error (failure expected)
+  set_fact:
+    foo: '{{lookup("config", "THIS_DOES_NOT_EXIST", on_missing="error")}}'
+  ignore_errors: yes
+  register: lookup_config_2
+
+- name: Verify lookup_config does not error with on_missing=skip
+  set_fact:
+    lookup3: '{{lookup("config", "THIS_DOES_NOT_EXIST", on_missing="skip")}}'
+  register: lookup_config_3
+
+# TODO: Is there a decent way to check that the warning is actually triggered?
+- name: Verify lookup_config does not error with on_missing=warn (warning expected)
+  set_fact:
+    lookup4: '{{lookup("config", "THIS_DOES_NOT_EXIST", on_missing="warn")}}'
+  register: lookup_config_4
+
+- name: Verify lookup_config errors with invalid on_missing (failure expected)
+  set_fact:
+    foo: '{{lookup("config", "THIS_DOES_NOT_EXIST", on_missing="boo")}}'
+  ignore_errors: yes
+  register: lookup_config_5
+
+- name: Verify lookup_config errors with invalid param type (failure expected)
+  set_fact:
+    foo: '{{lookup("config", 1337)}}'
+  ignore_errors: yes
+  register: lookup_config_6
+
+- name: Verify lookup_config errors with callable arg (failure expected)
+  set_fact:
+    foo: '{{lookup("config", "ConfigManager")}}'
+  ignore_errors: yes
+  register: lookup_config_7
+
+- name: Verify lookup_config
+  assert:
+    that:
+      - '"meow" in lookup("config", "ANSIBLE_COW_WHITELIST")'
+      - lookup_config_1 is failed
+      - '"Unable to find setting" in lookup_config_1.msg'
+      - lookup_config_2 is failed
+      - '"Unable to find setting" in lookup_config_2.msg'
+      - lookup_config_3 is success
+      - 'lookup3|length == 0'
+      - lookup_config_4 is success
+      - 'lookup4|length == 0'
+      - lookup_config_5 is failed
+      - '"must be a string and one of" in lookup_config_5.msg'
+      - lookup_config_6 is failed
+      - '"Invalid setting identifier" in lookup_config_6.msg'
+      - lookup_config_7 is failed
+      - '"Invalid setting" in lookup_config_7.msg'