refactor: improve python integration by using magick method and properties

[SMoraisAnsys]

This PR is currently a WIP. The changes are:

• using __getitem__ instead of the get_item method that was implemented. The great thing with that change is that any use can now call speos_client[my_key] instead of speos_client.get_item(key=my_key). It's a good practice to implement magick methods when they make sense.
• using Python property to propose something simple to our users while hidding the complexity. This way, a user will think he is playing with an attribute when, behind the scene, there is something complexe going on. It is also a good practice in Python.

Note

I used property for the Face class, if the change is accepted, we can think about applying it to all script files

[StefanThoene]

@SMoraisAnsys in regards to the properties: How to combine the properties with the usage of fluent API methodology currently implemented.

in regards for the getitem i didn't know about that magic method. so great idea

[SMoraisAnsys]

Closing as superseded by the POC #453