Instead of passing a GlobalObject everywhere, we will simply pass a VM,
from which we can get everything we need: common names, the current
realm, symbols, arguments, the heap, and a few other things.
In some places we already don't actually need a global object and just
do it for consistency - no more `auto& vm = global_object.vm();`!
This will eventually automatically fix the "wrong realm" issue we have
in some places where we (incorrectly) use the global object from the
allocating object, e.g. in call() / construct() implementations. When
only ever a VM is passed around, this issue can't happen :^)
I've decided to split this change into a series of patches that should
keep each commit down do a somewhat manageable size.
The NumberFormat spec casually indicates the need for a PluralRules
object without explicity saying so, with text such as:
"which may depend on x in languages having different plural forms."
Other implementations actually do create a PluralRules object to resolve
those cases with ResolvePlural. However, ResolvePlural doesn't need much
from PluralRules to operate, so this can be abstracted out for use in
NumberFormat without the need to allocate a PluralRules instance.
The JS::Intl enum was added when implementing the PluralRules
constructor. Now that LibUnicode has a plural rules implementation,
replace the JS::Intl enum with the analagous Unicode enum.
