Deprecate InspectHandles

[Kaffeine]

InspectHandles removed in Telepathy 1.0 by commit

Remove InspectHandles
Identifiers are always given together with handles, so it must never be needed to inspect an handle.

This makes sense, so we need to:

1. Mark the method as deprecated in 0.27.x spec
2. Ensure that the method is deprecated at https://telepathy.freedesktop.org/spec/Connection.html
3. Deprecate the method in client-side bindings
4. Deprecate the method in service-side bindings
5. Maybe even provide default implementation via GetContactAttributes().