Moving v4overlay and dualstackoverlay to just 'overlay' in CNI

[pjohnst5]

Here's the general idea:

• We change the conflists to 'overlay' for both dualstack and v4overlay, as well as make CNI capable of handling this 'overlay' option
• We release this CNI and conflist change to AKS together (as always, since it's in a .tar file)
• Update AKS to use this new CNI (dropgz) version
• Roll that out to all of AKS
  ---- This is where all AKS clusters, have the same conflist now (basically) ----
  • The only clusters with different conflists, would be v4overlay linux using generator: true, but that would work the same as now

Final cleanup stage

• In CNS, add a third 'overlay' generator, which generates 'overlay' conflist (without v4swift execution mode)
• Release it in AKS
• Change CNS configmap in AKS to use 'overlay' conflist generation
• Remove 'dualstack' and 'v4overlay' options completely in CNS and CNI (generators, conflists, if statements, all of it)

[rbtr]

/cc @thatmattlong for awareness

[pjohnst5]

• Will also add CNS generator in this PR (even thoug it won't be used yet in AKS, until CNI is updated)
  Edit: Nvm, will make CNS generator it's own PR, to keep things scoped to 1 component only per PR

[pjohnst5]

Tested this on a v4overlay cluster and pod to pod connectivity worked for both linux and windows
overlay-notes-and-testing.zip

[rbtr]

lgtm but I will defer to @tamilmani1989 to approve

[tamilmani1989]

lgtm