When overriding constructors, we need to call the parent constructor, otherwise GObject will not be properly initialized:

>>> from importlib import import_module; ufia = import_module('examples.update-file-info-async')
>>> ufia.UpdateFileInfoAsync()
<update-file-info-async.UpdateFileInfoAsync object at 0x7f5fe326b5c0 (uninitialized at 0x(nil))>


Furthermore, we can drop the constructors where we are not initializing any extra properties –
then the constructor of the parent class (GObject will be called).

We also need to ensure that GObject is the first parent class listed since otherwise,
Python will try to call the constructor of the provider, which does not exist since it is an abstract class.

We will keep it for TestExtension since it is the first example people reading the docs will see
and hopefully that will reduce the amount of forgotten parent constructor calls.


Noticed in https://github.com/linuxmint/nemo-extensions/commit/67a5d42489a1ae1715f620f281b62b8cc444d2d0