Merge changes from install.sh into install-pre-1.16.sh.

Some user upgrade form 1.6 to 1.7 by just change the image. The crds and rbacs are not updated, however the controller starts successfully and hide the issues. This check will panic kube-ovn-controller if crds are not ready and expose the issues.

Gateway node(s) forward egress traffic to external gateway based on
policy routing. Support both distributed and centralized gateway modes.
New properties are available in subnet spec: externalGateway,
policyRoutingPriority & policyRoutingTableID.

When the node that runs northd power off,
the lock to southbound will not released.
Use ep to store the norhtd leader and try
to release lock if no alive northd.

For some unknown reason, kernel will report "UDP bad checksum" and drop packet, disable validation to bypass this issue

Optimize Command

fix building error

fix: check error vaule

feat: vpc nat gateway

feat: vpc nat gateway

feat: vpc nat gateway

Support the other OVS commands

Fix https://github.com/alauda/kube-ovn/issues/655

lr-route-list
ls-lb-list
acl