[enh] new command 'app change-label'

data/actionsmap/yunohost.yml

@@ -647,6 +647,19 @@ app:
                 authenticate: all
                 authenticator: ldap-anonymous
 
+        ### app_change_label()
+        change-label:
+            action_help: Change an application label
+            api: PUT /apps/<app>/label
+            configuration:
+                authenticate: all
+                authenticator: ldap-anonymous
+            arguments:
+                app:
+                    help: the application id
+                new_label:
+                    help: the new application label
+
         ### app_addaccess() TODO: Write help
         addaccess:
             action_help: Grant access right to users (everyone by default)

src/yunohost/app.py

@@ -1320,6 +1320,17 @@ def app_ssowatconf(auth):
     logger.success(m18n.n('ssowat_conf_generated'))
 
 
+def app_change_label(auth, app, new_label):
+    installed = _is_installed(app)
+    if not installed:
+        raise MoulinetteError(errno.ENOPKG,
+                              m18n.n('app_not_installed', app=app))
+
+    app_setting(app, "label", value=new_label)
+
+    app_ssowatconf(auth)
+
+
 def _get_app_settings(app_id):
     """
     Get settings of an installed app