Update validate-modules (#20932)

* Update validate-modules

* Validates ANSIBLE_METADATA
* Ensures imports happen after documentation vars
* Some pep8 cleanup

* Clean up some left over unneeded code

* Update modules for new module guidelines and validate-modules checks

* Update imports for ec2_vpc_route_table and ec2_vpc_nat_gateway

lib/ansible/modules/system/gconftool2.py

@@ -16,9 +16,10 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
-from ansible.module_utils.basic import AnsibleModule, BOOLEANS_TRUE
-from ansible.module_utils.pycompat24 import get_exception
-import subprocess
+
+ANSIBLE_METADATA = {'status': ['preview'],
+                    'supported_by': 'community',
+                    'version': '1.0'}
 
 DOCUMENTATION = """
 module: gconftool2
@@ -101,6 +102,10 @@ RETURN = '''
 ...
 '''
 
+from ansible.module_utils.basic import AnsibleModule, BOOLEANS_TRUE
+from ansible.module_utils.pycompat24 import get_exception
+import subprocess
+
 
 class GConf2Preference(object):
     def __init__(self, ansible, key, value_type, value,