Differentiate between behavioral and variable type parameters

[Gabriel-Darbord]

Currently there is a single entity to represent all type parameters: FASTJavaTypeParameterExpression.
However, the same type parameter expression is not always applicable on both behavioral entities (classes and methods) and variables.
The ones applied to behaviorals can define an upper bound, which is how the current entity works:

// on class
class MyClass<T extends Object> {} // OK
// on method
<T extends Object> void f() {} // OK
// on variable
MyClass<T extends Object> obj; // NOK