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.

overseerr-api.yml

@@ -62,6 +62,9 @@ components:
         applicationUrl:
           type: string
           example: https://os.example.com
+        trustProxy:
+          type: boolean
+          example: true
         csrfProtection:
           type: boolean
           example: false