Add Deno global namespace

[kitsonk]

Resolves #1705

This PR adds the Deno APIs as a global namespace named Deno. For backwards compatibility, the ability to import * from "deno" is preserved. I have tried to convert every test and internal code the references the module to use the namespace instead, but because I didn't break compatibility I am not sure.

On the REPL, deno no longer exists, replaced only with Deno to align with the regular runtime.

The runtime type library includes both the namespace and module. This means it duplicates the whole type information. When we remove the functionality from the runtime, it will be a one line change to the library generator to remove the module definition from the type library.

I marked a TODO in a couple places where to remove the "deno" module, but there are additional places I know I didn't mark.

[ry]

Radical! LGTM - no comments.

I think this warrants bumping to v0.3.0 on the next release (which I was considering doing anyway)

[thgh]

How about adding a deprecation notice?

[sholladay]

IMO deno > Deno because it's not a constructor. There are at least a few exceptions to this convention at the language level, though, so not a big deal...

[kitsonk]

The convention for global namespaces in ECMAScript is to capitalise as pointed out by Burt in the main issue, which is why we did what what we did.