Add swapActiveStatsMap API for NetworkStatsFactory

This CL should be reverted before T sdk finalized.
This API is temporary added for the NetworkStatsFactory which is platform
code but will be moved into connectivity (tethering) mainline module.

Bug: 209935649
Test: atest CtsHostsideNetworkTests
Change-Id: I5894450f3089b2ea105722a18ddf8f1eed1c28a0
4 files changed