std: remove wildcard export in uuid module

[axetroy]

wildcard exports is a bad practice

export default function xxx() {
}

currently ✖️

import defaultGenerate, { v4 } from "https://deno.land/x/std/uuid/mod.ts" 
import generate from "https://deno.land/x/std/uuid/v4.ts" 

defaultGenerate();
generate();
v4();

Goal ☑️

import { v4 } from "https://deno.land/x/std/uuid/mod.ts" 
import { generate } from "https://deno.land/x/std/uuid/v4.ts" 

v4.generate();
generate();

[kt3k]

I like the idea.

[ry]

LGTM