fmt hyperlinked CLI text

**Is your feature request related to a problem? Please describe.**

A function for creating hyperlinked text to print to CLI output (see [_Hyperlinks (a.k.a. HTML-like anchors) in terminal emulators_](https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda)).

Not sure whether this should go under `fmt/colors` or a new `fmt/ansi`. `fmt/colors` makes most sense to me given it already contains various formatting functionality that doesn't strictly relate to color.

Example:

```ts
console.log("\x1B]8;;https://deno.land\x07Deno dot land\x1B]8;;\x07")
```

^ prints in CLI console as [Deno dot land](https://deno.land).

**Describe the solution you'd like**

Something like this:

```ts
export function hyperlink(text: string, url: string | URL) {
return `\x1B]8;;${url}\x07${text}\x1B]8;;\x07`
}
```

**Describe alternatives you've considered**

* What should `NO_COLOR` output be? Maybe a markdown equivalent like `[Deno dot land](https://deno.land)`? Edit: or maybe not, this could easily break layouts. Probably best to just print the text without the hyperlink.
* This feature isn't supported by all TTY environments — is there some way of feature detecting it? (Probably not). Per the gist linked above, all ECMA-48-compliant terminals that don't implement the feature simply fall back to showing the text with no hyperlink.