Cleanup - use is_boto3_error_(message|code) (ansible-collections#268)

* Reorder imports
* Make use of is_boto3_error_message
* Mass-migration over to is_boto3_error_code
* Remove unused imports
* unused vars in exception
* Improve consistency around catching BotoCoreError and ClientError
* Remove unused imports
* Remove unused 'PolicyError' from iam_policy_info
* Avoid catching botocore.exceptions.ClientError when we only want some error codes
* Import camel_dict_to_snake_dict/snake_dict_to_camel_dict from ansible.module_utils.common.dict_transformations

This commit was initially merged in https://github.com/ansible-collections/community.aws
See: ansible-collections@4cf52ef

plugins/modules/iam_password_policy.py

@@ -103,8 +103,10 @@
 except ImportError:
     pass  # caught by AnsibleAWSModule
 
+from ansible.module_utils.common.dict_transformations import camel_dict_to_snake_dict
+
 from ansible_collections.amazon.aws.plugins.module_utils.core import AnsibleAWSModule
-from ansible_collections.amazon.aws.plugins.module_utils.ec2 import camel_dict_to_snake_dict
+from ansible_collections.amazon.aws.plugins.module_utils.core import is_boto3_error_code
 
 
 class IAMConnection(object):
@@ -169,11 +171,10 @@ def update_password_policy(self, module, policy):
     def delete_password_policy(self, policy):
         try:
             results = policy.delete()
-        except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
-            if e.response['Error']['Code'] == 'NoSuchEntity':
-                self.module.exit_json(changed=False, task_status={'IAM': "Couldn't find IAM Password Policy"})
-            else:
-                self.module.fail_json_aws(e, msg="Couldn't delete IAM Password Policy")
+        except is_boto3_error_code('NoSuchEntity'):
+            self.module.exit_json(changed=False, task_status={'IAM': "Couldn't find IAM Password Policy"})
+        except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:  # pylint: disable=duplicate-except
+            self.module.fail_json_aws(e, msg="Couldn't delete IAM Password Policy")
         return camel_dict_to_snake_dict(results)