Provide system and gettext as ESM

[naipotato]

Both system and gettext are currently available to be imported as ECMAScript Modules, I think since GJS supports ESM. It would be nice to be able to import them in such a way using ts-for-gir, since the default GNOME Builder template imports system that way :)

[JumpLink]

I agree, we should support the following as ambient modules:

import gettext from 'gettext';
import system from 'system';

This should also work:

import { exit } from 'system';
import { ngettext as _ } from 'gettext';

Support for ambient modules will come with #106, but system and gettext are not supported at the moment, but I will add them. Are there more such imports?

[CharlieQLe]

Cairo is another one like this, it doesn't use the gi:https:// format as far as I know. However, Cairo does not provide named exports according to the docs.

[JumpLink]

Added in #106, for cairo I have create a new issue, see #118