Until now, object manager could only match pw global properties on
pw global objects, because this is the only available properties set
at the time the registry creates the global.
With this change, the object manager will now bind the proxy
if the type and the pw global properties have matched and will wait
until the proxy is available with all of its properties and tries
the check again.
This adds WP_SESSION_ITEM_FEATURE_ACTIVE and WP_SESSION_ITEM_FEATURE_EXPORTED
features, so _activate and _export APIs have been removed. Modules and unit
tests have also been updated.
It can be a bit tricky because the "installed" signal may be fired
from inside the context of wp_core_install_object_manager(),
in which case the main loop should not be executed (or it will never quit)
