This is a continuation of the previous five commits.
A first big step into the direction of no longer having to pass a realm
(or currently, a global object) trough layers upon layers of AOs!
Unlike the create() APIs we can safely assume that this is only ever
called when a running execution context and therefore current realm
exists. If not, you can always manually allocate the Error and put it in
a Completion :^)
In the spec, throw exceptions implicitly use the current realm's
intrinsics as well: https://tc39.es/ecma262/#sec-throw-an-exception
Intl.DisplayNames v2 adds "calendar" and "dateTimeField" types, as well
as a "languageDisplay" option for the "language" type. This just adds
these options to the constructor.
Intl.DisplayNames was the first Intl object implemented, and at that
point all AOs were just put into the main Intl AO header. But AOs that
belong to specific objects belong in that object's header. So this moves
CanonicalCodeForDisplayNames to the Intl.DisplayNames header.
