Add a method `all` to get all existing studies

[MaximeMorille]

This method aims to list all studies of ModelBuider. It takes the following parameters:

Attribute	Required	Type	Notes
page		number	Default value: 1
size		number	Default value: 20
memorybase		MemoryBase	Used to filter studies by memory base (Default value: None)

Documentation: https://braincube.pages.ipleanware.com/apps/model-builder/model-builder-back/openapi/#/Model%20Builder/get_studies