Add NetworkUtils utilities to SystemApi

attach*Filter and addArpEntry are necessary for the NetworkStack but are
only usable for apps that have system permissions.
Also includes system API for IpPrefix, LinkAddress, LinkProperties,
Network, and static modifier in ApfCapabilities that were missed in
previous CLs.

Test: Builds, flashed, WiFi works
Bug: 112869080
Change-Id: If141ae6a2f9145f5af64ba002ca44938f39b90a9