Generate Equality Check for entities

[badetitou]

This PR aims to add in the generator the code to generate equality checks (method = and hash). We keep the current default behavior -> no breaking change possible :)

I propose adding a method named: withEqualityCheckOn: that takes the list of properties as input to check for equality. It then generates the = and hash methods considering this list.

I have modified FamixTest4Generator to take into consideration this update. For instance, I added to person a firstName and lastName. And I added the quality check on them

    person property: #firstName type: #String.
    person property: #lastName type: #String.
    person withEqualityCheckOn: { #firstName. #lastName }.

The same for book with an id

I update the setup to add identity information. And I added the test testEqualityStudent to particularly test this feature

For method =

The generation follows this pattern:

= aFamixTest4Person 

    <generated>
    ^ aFamixTest4Person firstName = self firstName and: [ aFamixTest4Person lastName = self lastName] 

And for hash

hash

    <generated>
    ^ self firstName hash bitXor: self lastName hash 

I based this template on existing methods in the system