Refactor GizaModel

[Gonmeso]

When creating the tests for the GizaModel there were a lot of patching involved, multiple client calls, and thus in makes it harder also to test GizaAgent as it is an extension of the model.

When encountering such needs for patching in the test, that also indicates that we might have over complicated the design of GizaModel, specially the __init__.

We should aim to improve the design of this entity to:

• Provide a better public API
• Ease testing
• Add corner cases handling
• Create specific exceptions regarding model usage

This changes should not affect the current usage if the predict method, as it is basically the entrypoint used by the users, but the underlying logic can be greatly improved.

[LuisDi98]

I would like to take this issue. Solid designs principles may improve this init()
Do we have any group in case of deeper questions about the project?

[Gonmeso]

Hi @LuisDi98 I've assigned it to you, have in mind that designing will need also input fro our side.

[LuisDi98]

Sorry... I've been having troubles with personal stuff... And I consider is better to unassign it... The ODHack6.0 is coming soon the July 25th. I'm really sorry for not completing the issue, thanks a lot for the chance @Gonmeso
I hope the new dev can fix it 🔥