binder: Add method to enable RT inheritance for all Binders in process

It may be useful to enable RT inheritance for all Binders within a
process (for example, system_server). Today, if you want to do that, you
need to call setInheritRt for each new Binder. However, in a situation
where your process has a lot of services (ex: system_server) this needs
to be called in a lot of places, and it would be easy to miss one.

This change adds a feature to add a global flag that specifies that all
binders should have RT inheritance enabled, so rather than call
setInheritRt when creating each individual service, you can call
setGlobalInheritRt to make sure that every new service created
afterwards will get the inherit_rt flag.

Flag: android.server.allow_system_server_inherit_rt
bug: 397169625
Change-Id: Ic03d2cbc073e461505a435c94cfc083974e5f5a8