Support named export variable declaration destructuring

[jaydenseric]

Fixes #1 .

[jaydenseric]

Here is what I've been messing around with in AST explorer:

export const a = true;
export var b, c, d = true;
export const { e, f: i } = { e: true, f: true };
export const [g, h] = [true, true];
export const [, j] = [true, true];
export const { k, l: { m: [n]} } = { k: true, l: { m: [true] } };
export const { o, ...p } = { o: true, b: true, c: true };
export const [, ...q] = [1, 2];