Show user's Matrix ID and device ID in developer settings tab (#2559)

public/locales/en-GB/app.json

@@ -59,6 +59,7 @@
     "username": "Username",
     "video": "Video"
   },
+  "device_id": "Device ID: {{id}}",
   "disconnected_banner": "Connectivity to the server has been lost.",
   "full_screen_view_description": "<0>Submitting debug logs will help us track down the problem.</0>",
   "full_screen_view_h1": "<0>Oops, something's gone wrong.</0>",
@@ -99,6 +100,7 @@
   "login_auth_links_prompt": "Not registered yet?",
   "login_subheading": "To continue to Element",
   "login_title": "Login",
+  "matrix_id": "Matrix ID: {{id}}",
   "microphone_off": "Microphone off",
   "microphone_on": "Microphone on",
   "mute_microphone_button_label": "Mute microphone",