Cleanup headers and imports (ansible-collections#1738)

Cleanup headers and imports

SUMMARY
Mass update of imports, docs fragments and file headers

Many of the amazon.aws module_utils and docs fragments got moved about, update community.aws to reflect this.
Consistently apply the comment headers as documented at https://docs.ansible.com/ansible/devel/dev_guide/developing_modules_documenting.html#python-shebang-utf-8-coding

ISSUE TYPE

Docs Pull Request
Feature Pull Request

COMPONENT NAME
ADDITIONAL INFORMATION
Header cleanup based upon:
https://docs.ansible.com/ansible/devel/dev_guide/developing_modules_documenting.html#python-shebang-utf-8-coding

Begin your Ansible module with #!/usr/bin/python - this “shebang” allows ansible_python_interpreter to work. Follow the shebang immediately with # -*- coding: utf-8 -*- to clarify that the file is UTF-8 encoded.

and
https://docs.ansible.com/ansible/devel/dev_guide/developing_modules_documenting.html#copyright-and-license

After the shebang and UTF-8 coding, add a copyright line with the original copyright holder and a license declaration. The license declaration should be ONLY one line, not the full GPL prefix.
...
Additions to the module (for instance, rewrites) are not permitted to add additional copyright lines other than the default copyright statement if missing:

Reviewed-by: Alina Buzachis

This commit was initially merged in https://github.com/ansible-collections/community.aws
See: ansible-collections/community.aws@a4f20bf

plugins/modules/ec2_transit_gateway.py

@@ -1,12 +1,10 @@
 #!/usr/bin/python
+# -*- coding: utf-8 -*-
+
 # Copyright: Ansible Project
 # GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
 
-from __future__ import absolute_import, division, print_function
-__metaclass__ = type
-
-
-DOCUMENTATION = '''
+DOCUMENTATION = r"""
 module: ec2_transit_gateway
 short_description: Create and delete AWS Transit Gateways
 version_added: 1.0.0
@@ -74,13 +72,13 @@
 author:
   - "Bob Boldin (@BobBoldin)"
 extends_documentation_fragment:
-  - amazon.aws.aws
-  - amazon.aws.ec2
+  - amazon.aws.common.modules
+  - amazon.aws.region.modules
   - amazon.aws.boto3
   - amazon.aws.tags
-'''
+"""
 
-EXAMPLES = '''
+EXAMPLES = r"""
 - name: Create a new transit gateway using defaults
   community.aws.ec2_transit_gateway:
     state: present
@@ -114,9 +112,9 @@
     region: ap-southeast-2
     transit_gateway_id: tgw-3a9aa123
   register: deleted_tgw
-'''
+"""
 
-RETURN = '''
+RETURN = r"""
 transit_gateway:
   description: The attributes of the transit gateway.
   type: complex
@@ -210,20 +208,25 @@
       returned: always
       type: str
       sample: tgw-3a9aa123
-'''
+"""
+
+from time import sleep
+from time import time
 
 try:
-    from botocore.exceptions import BotoCoreError, ClientError
+    from botocore.exceptions import BotoCoreError
+    from botocore.exceptions import ClientError
 except ImportError:
     pass  # handled by imported AnsibleAWSModule
 
-from ansible_collections.community.aws.plugins.module_utils.modules import AnsibleCommunityAWSModule as AnsibleAWSModule
-from time import sleep, time
-from ansible_collections.amazon.aws.plugins.module_utils.ec2 import ansible_dict_to_boto3_filter_list
-from ansible_collections.amazon.aws.plugins.module_utils.ec2 import AWSRetry
-from ansible_collections.amazon.aws.plugins.module_utils.ec2 import boto3_tag_list_to_ansible_dict
-from ansible_collections.amazon.aws.plugins.module_utils.ec2 import camel_dict_to_snake_dict
+from ansible.module_utils.common.dict_transformations import camel_dict_to_snake_dict
+
 from ansible_collections.amazon.aws.plugins.module_utils.ec2 import ensure_ec2_tags
+from ansible_collections.amazon.aws.plugins.module_utils.retries import AWSRetry
+from ansible_collections.amazon.aws.plugins.module_utils.tagging import boto3_tag_list_to_ansible_dict
+from ansible_collections.amazon.aws.plugins.module_utils.transformation import ansible_dict_to_boto3_filter_list
+
+from ansible_collections.community.aws.plugins.module_utils.modules import AnsibleCommunityAWSModule as AnsibleAWSModule
 
 
 class AnsibleEc2Tgw(object):