gio: Add DBusObjectManagerClient

[tautropfli]

Sadly all constructors are generated manually:

• new/new_future and new_for_bus/new_for_bus_future were not generated at all by gir (the *_future versions were generated, but I don't know how to set only the callback version to manually generated)
• new_sync and new_for_bus_sync were generated mostly fine. I only had to fix how the cancellable param is passed to ffi:

  - cancellable.to_glib_none().0,
  + cancellable.map(|p| p.as_ref()).to_glib_none().0,

  This looks like a bug in gir because for other methods with a cancellable the .map(...) part is added just fine.

[tautropfli]

I noticed that the implementation of GDBusObjectManagerClient uses a mutex internally, so I marked it as send+sync in Gir.toml.

Sadly the docs don't mention the MT safety like they do for other types such as DBusProxy, so I'm not entirely sure 😅 :

A GDBusProxy instance can be used from multiple threads [...]

[bilelmoussaoui]

You can update the gir submodule & regen, that should get rid of some of the manual code i hope :)

[tautropfli]

Wohoo that worked like a charm ✨

[sdroege]

This is not useful API. You can't construct a None very easily. It would be better to have two variants of this function, one with callback and one without

[sdroege]

Ah no, None is easy because you have it already defined as Box<dyn>. But the case where a callback is provided is not very convenient now as it requires wrapping in Some() and Box::new().

[tautropfli]

Ah dang it, I changed the async versions already to use two variants but forgot to do the same for the sync and the async+callback ones. Fixed in 23dac07 and 9728dcf

[sdroege]

Looks good to me otherwise. Do you also want to provide a small example making use of this?

[tautropfli]

Do you also want to provide a small example making use of this?

Yes, my plan was to make DBusProxy subclassable and then do an example with UDisks (because that's what I am using it for right now ^^).