Add type parameters to linearization

Add type parameters to linearization

Summary:
This diff adds type parameters to the list of things linearization stores. Each type parameterization of a class is a separate class when it comes to linearization. Consider the example test:

```
<?hh

interface Ico<+T> {}

interface I2 extends Ico<mixed> {}

interface I3 extends I2, Ico<num> {}

interface I4 extends I3, Ico<int> {}
```

this becomes:

```
L(I4) = I4 + L(I3) + L(Ico<int>)
        = I4 + [I3 + L(I2) + L(Ico<num>)] + Ico<int>
        = I4 + I3 + [I2 + L(Ico<mixed>)] + Ico<num> + Ico<int>
        = I4 + I3 + I2 + Ico<mixed> + Ico<num> + Ico<int>
        = [I4, I3, I2, Ico<mixed>, Ico<num>, Ico<int>]
```

which is correct according to our current behavior.

If you instead switch Ico<int> and I3, you get a completely different linearization.

Reviewed By: vassilmladenov

Differential Revision: D9757934

fbshipit-source-id: bad330eecd4117e459f28ddb57f01edf45453a2c