ipcache: Add unit tests for IP shadowing
ipcache: Add unit tests for IP shadowing

These unit tests validate the bug fixed by the prior commit where
entries dumped from the ipcache may not consistently map IPs to the
correct Identity. Note that there is a potential Golang map dump
ordering aspect to these tests so depending on the Go version used they
may/may not consistently fail. They consistently fail for me prior to
the fix (eg v1.8.0-rc1), and consistently pass with the fix, but YMMV.

Signed-off-by: Joe Stringer <16a9a54ddf4259952e3c118c763138e83693d7fd@cilium.io>

tklauser/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,cilium-team/cilium,cilium-team/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,tklauser/cilium,tklauser/cilium,cilium/cilium,cilium/cilium,tklauser/cilium,tgraf/cilium,tklauser/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,tgraf/cilium,tgraf/cilium