Add en-GB localisation (#5952)

* Create blank en-GB/messages.po

* localise certain strings for en-GB

* Update lingui.config.js

* Update dates.ts

* Update helpers.ts

* Update i18n.ts

* Update i18n.web.ts

* Update languages.ts

* Update i18n.ts

src/locale/i18n.ts

@@ -14,6 +14,7 @@ import {AppLanguage} from '#/locale/languages'
 import {messages as messagesCa} from '#/locale/locales/ca/messages'
 import {messages as messagesDe} from '#/locale/locales/de/messages'
 import {messages as messagesEn} from '#/locale/locales/en/messages'
+import {messages as messagesEn_GB} from '#/locale/locales/en-GB/messages'
 import {messages as messagesEs} from '#/locale/locales/es/messages'
 import {messages as messagesFi} from '#/locale/locales/fi/messages'
 import {messages as messagesFr} from '#/locale/locales/fr/messages'
@@ -53,6 +54,14 @@ export async function dynamicActivate(locale: AppLanguage) {
       ])
       break
     }
+    case AppLanguage.en_GB: {
+      i18n.loadAndActivate({locale, messages: messagesEn_GB})
+      await Promise.all([
+        import('@formatjs/intl-pluralrules/locale-data/en'),
+        import('@formatjs/intl-numberformat/locale-data/en-GB'),
+      ])
+      break
+    }
     case AppLanguage.es: {
       i18n.loadAndActivate({locale, messages: messagesEs})
       await Promise.all([