Creation of a generic class for demos

[laurenttainturier]

Actually, if we want to create a new demo, we need to copy and paste the code of a previous one.
The idea is to have a generic class Demo, in which we have some methods that can connect or disconnect functionalities, such as the temporal, consulDoc, etc.
Thus, to create a new demo, we will just need to create a new instance of this class and configure what we want to display on it, using its methods.