[NS B02] Split out a function to apply a NetworkReassignment

This makes the rematchAllNetworksAndRequests function, which
is the nexus of the rematching code, very straightforward and
easy to read.

Bug: 113554781
Test: FrameworksNetTests
Change-Id: I5cea4ed7e06439494700d88ab202b696402fa360
1 file changed