feat(ui): Move PROXY setting to UI (#782)

Users who have set PROXY=yes in their Docker containers will need to configure this setting in the UI and restart the container.

server/index.ts

@@ -61,7 +61,7 @@ app
     startJobs();
 
     const server = express();
-    if (process.env.PROXY === 'yes') {
+    if (settings.main.trustProxy) {
       server.enable('trust proxy');
     }
     server.use(cookieParser());

server/lib/settings.ts

@@ -54,6 +54,7 @@ export interface MainSettings {
   csrfProtection: boolean;
   defaultPermissions: number;
   hideAvailable: boolean;
+  trustProxy: boolean;
 }
 
 interface PublicSettings {
@@ -158,9 +159,10 @@ class Settings {
       main: {
         apiKey: '',
         applicationUrl: '',
-        hideAvailable: false,
         csrfProtection: false,
         defaultPermissions: Permission.REQUEST,
+        hideAvailable: false,
+        trustProxy: false,
       },
       plex: {
         name: '',