openvswitch: merge openvswitch-common + openvswitch-switch into openvswitch
openvswitch: organize openvswitch-ipsec and openvswitch-benchmark as subpackages
openswitch: add OVS_DEPENDS variable
openvswitch: change order of the installs

Also call Package/openvswitch/install for openvswitch-ipsec
and openvswitch-benchmark so that OVS base is installed for them too.
openvswitch: fix package URL