Refactor tether state change callback/broadcast for redactions

Refactor tether state change callback/broadcast to allow for redactions
based on the callback cookie of the recipient. This CL is a no-op and
will be used in a future CL to redact the SoftApConfiguration in
TetheringInterface.

Bug: 216524590
Test: atest TetheringTest CtsTetheringTests
Change-Id: I3684929e6ba832f4da353d48137967739ca558d6
1 file changed