Fix setImmediate polyfill args

[voces]

This fixes the setImmediate polyfill to accept rest-style args instead of an array to match Node.js.

// Actual node.js type signature
type setImmediate = <Args extends any[]>(fn: (...args: Args) => void, ...args: Args);

// Previous esm.sh type signature:
type setImmediate = <Args extends any[]>(fn: (...args: Args) => void, args: Args);

The previous behavior would result in setImmediate performing differently. If no arguments were passed or the first argument was not iterable, an exception would be thrown. If the first argument was iterable, it'd be passed as a spread result. I created an example npm module and ran it in deno repl as an example:

> const examples = await import("http://esm.sh/esm-sh-set-immediate-test").then(i => i.default);
> examples.withArray()
> foo bar // expected args [["foo", "bar"]], got ["foo", "bar"]
> examples.withArgs();
> f o o // expected args ["foo", "bar"], got ["f", "o", "o"]
> examples.withNone();
// expected args [], got below exception
Uncaught TypeError: args is not iterable (cannot read property undefined)
    at __setImmediate$ (https://cdn.esm.sh/v41/esm-sh-set-immediate-test@1.0.0/deno/esm-sh-set-immediate-test.js:2:37)
    at Object.withNone (https://cdn.esm.sh/v41/esm-sh-set-immediate-test@1.0.0/deno/esm-sh-set-immediate-test.js:2:833)
    at <anonymous>:2:10

[ije]

lgtm, thanks