Add support for x-trusted-proxy

* Increase the surface area of the set of headers that the proxy list
  feature looks at for the remote proxy IF x-trusted-proxy is valid.

awx/api/views/__init__.py

@@ -61,6 +61,7 @@ import pytz
 from wsgiref.util import FileWrapper
 
 # django-ansible-base
+from ansible_base.lib.utils.requests import get_remote_hosts
 from ansible_base.rbac.models import RoleEvaluation, ObjectRole
 from ansible_base.resource_registry.shared_types import OrganizationType, TeamType, UserType
 
@@ -2770,12 +2771,7 @@ class JobTemplateCallback(GenericAPIView):
         host for the current request.
         """
         # Find the list of remote host names/IPs to check.
-        remote_hosts = set()
-        for header in settings.REMOTE_HOST_HEADERS:
-            for value in self.request.META.get(header, '').split(','):
-                value = value.strip()
-                if value:
-                    remote_hosts.add(value)
+        remote_hosts = set(get_remote_hosts(self.request))
         # Add the reverse lookup of IP addresses.
         for rh in list(remote_hosts):
             try: