Make the health controller more robust and extensible by adding in
constants for heart beats instead of 3 character random strings that are
easy to get wrong.
Upgrades to Go 1.21.7 now that Go 1.20 is no longer being maintained.
It also, resolves the race conditions that we were seeing with BGP
server tests when we upgraded from 1.20 -> 1.21. This appears to be
because some efficiency changed in 1.21 that caused BGP to write to the
events at the same time that the test harness was trying to read from
them. Solved this in a coarse manner by adding surrounding mutexes to
the test code.
Additionally, upgraded dependencies.
This adds a simple controller that will watch for services of type LoadBalancer
and try to allocated addresses from the specified IPv4 and/or IPv6 ranges.
It's assumed that kube-router (or another network controller) will announce the addresses.
As the controller uses leases for leader election and updates the service status new
RBAC permissions are required.
