Allow calling signal-cli without -u flag

For daemon command all local users will be exposed as dbus objects
If only one local user exists, all other commands will use that user,
otherwise a user has to be specified.

src/main/java/org/asamk/signal/commands/MultiLocalCommand.java

@@ -0,0 +1,17 @@
+package org.asamk.signal.commands;
+
+import net.sourceforge.argparse4j.inf.Namespace;
+
+import org.asamk.signal.manager.Manager;
+
+import java.util.List;
+
+public interface MultiLocalCommand extends LocalCommand {
+
+    int handleCommand(Namespace ns, List<Manager> m);
+
+    @Override
+    default int handleCommand(final Namespace ns, final Manager m) {
+        return handleCommand(ns, List.of(m));
+    }
+}