Add a handler thread check to all public methods

To ensure that all access to the MdnsServiceTypeClient is done on
the handler thread, a handler thread check must be added to all
public methods in the MdnsServiceTypeClient. This will allow the
synchronized lock to be removed in future changes, and it will
also ensure that MdnsServiceTypeClient can access MdsServiceCache
properly.

Bug: 265787401
Test: atest FrameworksNetTests
Change-Id: I0206874eb0acdf0272b8ad23d29f3e764bfdec38