Qualify references to WifiNetworkSuggestions

Connectivity's metalava invocation does not depend on framework-wifi,
so these references fail to resolve, and as a result metalava currently
removes the import.

Fully qualify the references instead, to avoid both metalava trying
to resolve the dependency, and having to depend on framework-wifi just
for javadoc.

Bug: 186197911
Test: build the sdk (with connectivity module stubs as input)
Change-Id: I7129821b9a0d08d06f8e977a3c17fa5f5f6f9cee
2 files changed