Fix Memory Consumption in network_policy_controller (#902)

* feat(gitignore): don't track intellij files

* fact(network_policy): networkPoliciesInfo -> stack

Take networkPoliciesInfo off of the npc struct and convert it to a stack
variable that is easy to cleanup.

* fix(network_policy): k8s obj memory accumulation

Kubernetes informers will block on handler execution and will then begin
to accumulate cached Kubernetes object information into the heap. This
change moves the full sync logic into it's own goroutine where full
syncs are triggered and gated via writing to a single item channel.

This ensures that:
- Syncs will only happen one at a time (as they are full syncs and we
  can't process multiple at once)
- Sync requests are only ever delayed and never lost as they will be
  added to the request channel
- After we make a sync request we return fast to ensure that the handler
  execution returns fast and that we don't block the Kubernetes
  informers

* fact(network_policy): rework readyForUpdates

Now that we are better managing requests for full syncs we no longer
need to manage readyForUpdates on the npc controller. We already enforce
not blocking the handlers and a single sync execution chain, whether it
comes from the controller in the form of a periodic sync or whether it
comes from a Kubernetes informer, either way the result is a
non-blocking, single thread of execution, full sync.

* fix(network_policy): address PR feedback

Author: aauren

.gitignore

@@ -1,4 +1,5 @@
 .vscode
+.idea
 /kube-router
 /gobgp
 _output