Special handling when applying mapped types to array and tuple types

[kevinbarabash]

We want the following behaviour:

type A = [number, string];
type B = A[number];

type Foo<T> = {
   [K in keyof T]: T[K][]
};

type X = Foo<A>; // [number[], string[]]
type Y = Foo<number[]>; // number[][]

Right now Escalier produces the following types:

type X = Foo<A>: // {0: string[], 1: number[]}
type Y = Foo<number[]>; // {[K]: string[] for K in number}