Remove framework code that has moved to frameworks/libs/net

Add srcs to framework and change import path.
Remove the codes which are moved to frameworks/libs/net.

Bug: 139268426
Bug: 135998869
Bug: 138306002
Bug: 143925787
Test: atest FrameworksNetTests
      atest FrameworksTelephonyTests
      ./frameworks/opt/net/wifi/tests/wifitests/runtests.sh

Change-Id: I44e0a8361637c2d43be2e5d033d405b22e1a149c
Merged-In: I067cdc404e5a63947c19cb75069a39ae42faa3c8
Merged-In: Ieb8927f9af7f87a5ae038bd6c7daeb3d70117fef