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
      atest ./frameworks/opt/net/wifi/tests/wifitests/runtests.sh
Change-Id: Ieb8927f9af7f87a5ae038bd6c7daeb3d70117fef