feat(auth): Add optional CSRF protection (#697)

* fix(auth): Missing CSRF middleware
Resolves LGTM alert/error for query js/missing-token-validation
More info: https://lgtm.com/rules/1506064038914/

overseerr-api.yml

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