Add Network.fromNetworkHandle()

This is the counterpart to Network.getNetworkHandle() and facilitates
native code calling back to Java with network handle values from
getNetworkHandle.

Bug: 77210159
Bug: 64148938
Test: make CtsNetTestCases

Change-Id: I032b959d84180c063a79ddd97c35e7384b0f50a1
2 files changed