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

test/sanity/validate-modules/schema.py

@@ -43,3 +43,13 @@ doc_schema = Schema(
     },
     extra=ALLOW_EXTRA
 )
+
+metadata_schema = Schema(
+    {
+        Required('status'): [Any('stableinterface', 'preview', 'deprecated',
+                                 'removed')],
+        Required('version'): '1.0',
+        Required('supported_by'): Any('core', 'community', 'unmaintained',
+                                      'committer')
+    }
+)