Make it possible to change Jitsi web UI language

Fixes #427 (Github Issue).

roles/matrix-jitsi/defaults/main.yml

@@ -51,6 +51,9 @@ matrix_jitsi_web_container_extra_arguments: []
 # List of systemd services that matrix-jitsi-web.service depends on
 matrix_jitsi_web_systemd_required_services_list: ['docker.service']
 
+matrix_jitsi_web_config_defaultLanguage: 'en'
+matrix_jitsi_web_interface_config_lang_detection: false
+
 
 matrix_jitsi_prosody_docker_image: "jitsi/prosody:4101"
 matrix_jitsi_prosody_docker_image_force_pull: "{{ matrix_jitsi_prosody_docker_image.endswith(':latest') }}"

roles/matrix-jitsi/templates/web/config.js.j2

@@ -263,7 +263,7 @@ hiddenDomain: {{ matrix_jitsi_recorder_domain|to_json }},
     // disable1On1Mode: false,
 
     // Default language for the user interface.
-    // defaultLanguage: 'en',
+    defaultLanguage: {{ matrix_jitsi_web_config_defaultLanguage|to_json }},
 
     // If true all users without a token will be considered guests and all users
     // with token will be considered non-guests. Only guests will be allowed to

roles/matrix-jitsi/templates/web/interface_config.js.j2

@@ -30,7 +30,7 @@ var interfaceConfig = {
     APP_NAME: 'Jitsi Meet',
     NATIVE_APP_NAME: 'Jitsi Meet',
     PROVIDER_NAME: 'Jitsi',
-    LANG_DETECTION: false, // Allow i18n to detect the system language
+    LANG_DETECTION: {{ matrix_jitsi_web_interface_config_lang_detection|to_json }}, // Allow i18n to detect the system language
     INVITATION_POWERED_BY: true,
 
     /**