Add progress bar to inventory sync

Some inventory syncs take a long time to complete.
This change adds in a progress bar so users know there is actual
progress and have an estimated completion time.

broker/providers/ansible_tower.py

@@ -549,7 +549,9 @@ def get_inventory(self, user=None):
         for inv in invs:
             inv_hosts = inv.get_related("hosts", page_size=200).results
             hosts.extend(inv_hosts)
-        return [self._compile_host_info(host) for host in hosts]
+        with click.progressbar(hosts, label='Compiling host information') as hosts_bar:
+            compiled_host_info = [self._compile_host_info(host) for host in hosts_bar]
+        return compiled_host_info
 
     def extend(self, target_vm, new_expire_time=None):
         """Run the extend workflow with defaults args