Move VCN utilities from services.jar to framework.jar

This patch moves the VCN utilities from the systemserver classpath
to boot classpath. In this way, the code consumers that do not
have the source code (previously framework.jar and now services.jar)
do not need to statically include the files anymore. It also removes
the burden of class jarjar

Bug: 288465472
Test: presubmit: FrameworksVcnTests, CtsVcnTestCases,
      FrameworksIkeTests, CtsIkeTestCases, VpnTest
Flag: EXEMPT code refactoring; no functional change
Change-Id: I7560a35727d62344c89f9a3b9ec9f0eb0058a1a2