Ensure events are serialized

[briandealwis]

@matthewmichihara reported seeing out-of-order events. Our event code fires off a separate goroutine for each event which can lead to out-of-sequence delivery. Change the event delivery to write directly to the event channel to ensure events are delivered in order.

[codecov]

Codecov Report

Merging #6064 (41a4b43) into master (5c2e24c) will decrease coverage by 0.45%.
The diff coverage is 77.77%.

@@            Coverage Diff             @@
##           master    #6064      +/-   ##
==========================================
- Coverage   70.77%   70.31%   -0.46%     
==========================================
  Files         462      471       +9     
  Lines       17897    18078     +181     
==========================================
+ Hits        12666    12712      +46     
- Misses       4299     4436     +137     
+ Partials      932      930       -2     

Impacted Files	Coverage Δ
pkg/skaffold/event/v2/event.go	79.74% <50.00%> (-0.09%)	⬇️
pkg/skaffold/event/event.go	91.10% <100.00%> (-0.87%)	⬇️
pkg/skaffold/deploy/deploy_mux.go	61.70% <0.00%> (-14.62%)	⬇️
pkg/skaffold/event/v2/application_logs.go	45.45% <0.00%> (-4.55%)	⬇️
pkg/skaffold/runner/v1/deploy.go	49.39% <0.00%> (-4.07%)	⬇️
pkg/skaffold/deploy/resource/deployment.go	85.36% <0.00%> (-3.62%)	⬇️
...affold/kubernetes/portforward/forwarder_manager.go	47.82% <0.00%> (-2.18%)	⬇️
...skaffold/kubernetes/debugging/container_manager.go	50.00% <0.00%> (-1.86%)	⬇️
pkg/skaffold/gcp/auth.go	23.33% <0.00%> (-1.67%)	⬇️
pkg/skaffold/deploy/kustomize/kustomize.go	74.66% <0.00%> (-1.03%)	⬇️
... and 44 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5c2e24c...41a4b43. Read the comment docs.

[MarlonGamez]

lgtm, thanks!