wifi(interface): Add RTT Controller object

Create a RTT controller object to use for initiating all the RTT related
HAL opertations.
Since we don't want to fix the iface on which to initiate RTT operations,
these methods will be rooted in a new standalone object |RttController|.
Framework can decide to intiate an instance of |RttController| on a
specified iface or let the implementation pick one.

Bug: 31991232
Test: Interface compiles.
Change-Id: I65f7a7babd72db26ce6549f572abd9ef73700c82