Add RTTController and corresponding aidl interface to wificond

Add RTTController and corresponding aidl interface to wificond

This add RttController interface as a lazy initialization object.
User can get an instance of RttController while register a RttClient
through wificond.

Currently HAL RttController has an optional parameter for choosing
on which network interface will RTT run. However, in order to
hide interface concept from RTT framework as well as keep simplicity,
we don't expose this interface choice via aidl to framework for now.

Bug: 31756849
Test: compile

Change-Id: I2a13374254fd8c6bd7911e5cfbe3297cde25e9e7