Add the ability to list projects based on a user

Essentially performing GET /users/{user_id}/projects

Change-Id: Iae6ddfc86a856fa24fbe293ec4af52ea671390f8
Closes-Bug: #1394793

doc/source/command-objects/project.rst

@@ -79,6 +79,7 @@ List projects
 
     os project list
         [--domain <domain>]
+        [--user <user>]
         [--long]
 
 .. option:: --domain <domain>
@@ -87,6 +88,12 @@ List projects
 
     .. versionadded:: 3
 
+.. option:: --user <user>
+
+    Filter projects by :option:`\<user\> <--user>` (name or ID)
+
+    .. versionadded:: 3
+
 .. option:: --long
 
     List additional fields in output

openstackclient/identity/v3/project.py

@@ -162,6 +162,11 @@ class ListProject(lister.Lister):
             metavar='<domain>',
             help='Filter projects by <domain> (name or ID)',
         )
+        parser.add_argument(
+            '--user',
+            metavar='<user>',
+            help='Filter projects by <user> (name or ID)',
+        )
         parser.add_argument(
             '--long',
             action='store_true',
@@ -178,9 +183,24 @@ class ListProject(lister.Lister):
         else:
             columns = ('ID', 'Name')
         kwargs = {}
+
+        domain_id = None
         if parsed_args.domain:
-            kwargs['domain'] = common.find_domain(identity_client,
+            domain_id = common.find_domain(identity_client,
-                                                  parsed_args.domain).id
+                                           parsed_args.domain).id
+            kwargs['domain'] = domain_id
+
+        if parsed_args.user:
+            if parsed_args.domain:
+                user_id = utils.find_resource(identity_client.users,
+                                              parsed_args.user,
+                                              domain_id=domain_id).id
+            else:
+                user_id = utils.find_resource(identity_client.users,
+                                              parsed_args.user).id
+
+            kwargs['user'] = user_id
+
         data = identity_client.projects.list(**kwargs)
         return (columns,
                 (utils.get_item_properties(