SigHelper: Make signature server optional and configurable

src/invidious.cr

@@ -153,6 +153,15 @@ Invidious::Database.check_integrity(CONFIG)
   {% puts "\nDone checking player dependencies, now compiling Invidious...\n" %}
 {% end %}
 
+# Misc
+
+DECRYPT_FUNCTION =
+  if sig_helper_address = CONFIG.signature_server.presence
+    IV::DecryptFunction.new(sig_helper_address)
+  else
+    nil
+  end
+
 # Start jobs
 
 if CONFIG.channel_threads > 0