Allow interaction authorization

[unfamiliarS]

I'm using this library to create a GUI shell for managing systemd daemons, and some issues emerged during development. When sending a DBus request to execute file system commands (such as EnableUnitFiles and DisableUnitFiles, see the systemd DBus API for more details: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.systemd1.html), the graphical user login window wouldn't appear, and an error would immediately be thrown:

org.freedesktop.dbus.exceptions.DBusExecutionException: Interactive authentication required.
        at java.base/jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62)
        at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:502)
        at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:486)
        at org.freedesktop.dbus.messages.Error.getException(Error.java:113)
        at org.freedesktop.dbus.messages.Error.throwException(Error.java:138)
        at org.freedesktop.dbus.RemoteInvocationHandler.executeRemoteMethod(RemoteInvocationHandler.java:241)
        at org.freedesktop.dbus.RemoteInvocationHandler.executeRemoteMethod(RemoteInvocationHandler.java:254)
        at org.freedesktop.dbus.RemoteInvocationHandler.executeRemoteMethod(RemoteInvocationHandler.java:156)
        at org.freedesktop.dbus.RemoteInvocationHandler.invoke(RemoteInvocationHandler.java:99)
        at jdk.proxy1/jdk.proxy1.$Proxy21.disableUnitFiles(Unknown Source)
        at de.thjom.java.systemd.Manager.disableUnitFiles(Manager.java:200)
        at com.shavarushka.models.sysd_commands.commands.DisableUnitCommand.execute(DisableUnitCommand.java:67)
        at com.shavarushka.controllers.SysdActionsC.lambda$18(SysdActionsC.java:199)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
        at java.base/java.lang.Thread.run(Thread.java:1583)

I read the DBus specification (https://dbus.freedesktop.org/doc/dbus-specification.html) and found a solution: add the 0x4 byte to the message header, which tells the receiving end to wait for authorization.

The code I'm proposing allows you to mark DBus methods in your client code that should allow interactive authorization. For example, here's how I use it:

    @DBusMemberName(value = "DisableUnitFiles")
    @MethodAllowInteractiveAutorization
    List<UnitFileChange> disableUnitFiles(List<String> names, boolean runtime);

    @DBusMemberName(value = "EnableUnitFiles")
    @MethodAllowInteractiveAutorization(value = true)
    Pair<Boolean, List<UnitFileChange>> enableUnitFiles(List<String> names, boolean runtime, boolean force);