IMS: Check for binderstate before calling endSession

ImsRegistrationListenerProxy listener, which is registered
as part of ImsManager.open, is not cleared even after moving
feature state to NOT_AVAILABLE because end session
is never called.

Check for binder state instead of feature state READY before
calling end session. End session will be triggered after
moving feature state to NOT_AVAILABLE.

Notify Ims state change only for the supported feature state
change to clients.

Test: Manual
Bug: 62816014
Change-Id: I1bb588ce2be9c181355ff744f43dad4e784e4ec5