Add V Wifi API signatures for Tethering

Add V Wifi API signatures for Tethering to reference for V+ platform.
Only the signatures are used, the APIs are nonfunctional until the next
SDK bump.

Bug: 216524590
Test: build
Change-Id: Id70ef693a9e7ca15525ec9f8695dede7a676a19e
Merged-In: Id70ef693a9e7ca15525ec9f8695dede7a676a19e
API-Coverage-Bug: 329783971
4 files changed