Internationalisation of javascript/m* directories

This is one of many MRs opened in order to improve the overall
internationalisation of the GitLab codebase.

i18n documentation
https://docs.gitlab.com/ee/development/i18n/externalization.html

app/assets/javascripts/mirrors/ssh_mirror.js

@@ -290,7 +290,7 @@ export default class SSHMirror {
         this.setSSHPublicKey(data.import_data_attributes.ssh_public_key);
       })
       .catch(() => {
-        Flash(_('Unable to regenerate public ssh key.'));
+        Flash(__('Unable to regenerate public ssh key.'));
       });
   }
 

app/assets/javascripts/monitoring/services/monitoring_service.js

 import axios from '../../lib/utils/axios_utils';
 import statusCodes from '../../lib/utils/http_status';
 import { backOff } from '../../lib/utils/common_utils';
-import { s__ } from '../../locale';
+import { s__, __ } from '../../locale';
 
 const MAX_REQUESTS = 3;
 
@@ -15,7 +15,7 @@ function backOffRequest(makeRequestCallback) {
           if (requestCounter < MAX_REQUESTS) {
             next();
           } else {
-            stop(new Error('Failed to connect to the prometheus server'));
+            stop(new Error(__('Failed to connect to the prometheus server')));
           }
         } else {
           stop(resp);

app/assets/javascripts/mr_popover/constants.js

+import { __ } from '~/locale';
+
 export const mrStates = {
   merged: 'merged',
   closed: 'closed',
 };
 
 export const humanMRStates = {
-  merged: 'Merged',
-  closed: 'Closed',
-  open: 'Open',
+  merged: __('Merged'),
+  closed: __('Closed'),
+  open: __('Open'),
 };

locale/gitlab.pot

@@ -3958,6 +3958,9 @@ msgstr ""
 msgid "Failed to check related branches."
 msgstr ""
 
+msgid "Failed to connect to the prometheus server"
+msgstr ""
+
 msgid "Failed to create repository via gitlab-shell"
 msgstr ""
 
@@ -9805,6 +9808,9 @@ msgstr ""
 msgid "Unable to load the diff. %{button_try_again}"
 msgstr ""
 
+msgid "Unable to regenerate public ssh key."
+msgstr ""
+
 msgid "Unable to schedule a pipeline to run immediately"
 msgstr ""