fix termination event not being sent

[tejal29]

In #4926 I added a new event to send a termination event to detect failures in skaffold setup.
However, during more rigorous testing, i saw some abnormalities where the event was received.

1. Send a nil event to indicate close of channel when skaffold terminates
2. Log all events.

Steps to Reproduce:

1. Please compile skaffold on this branch using make
2. Check if helm is installed and uninstall it or simple move.
3. if yes,

 sudo mv /usr/local/bin/helm ~/workspace/helm1

4. Open a new terminal

watch -n 0.5  "curl -H "Expect: any" localhost:50052/v1/events >> t.txt" 

5.. Checkout a skaffold helm example run skaffold dev

cd examples/helm-deployment
../../out/skaffold dev

6. Open t.txt and verify if "TerminationEvent" is done

{"result":{"timestamp":"2021-01-20T23:56:59.856262Z","event":{"metaEvent":{"entry":"Starting Skaffold: \u0026{Version:v1.17.1-75-g1f519d095-dirty ConfigVersion:skaffold/v2beta11 GitVersion: GitCommit:1f519d095243f08f3b3c4db72f3c585d763b4454 GitTreeState:dirty BuildDate:2021-01-20T15:47:23Z GoVersion:go1.15.3 Compiler:gc Platform:darwin/amd64}","metadata":{"build":{"numberOfArtifacts":1,"builders":[{"type":"DOCKER","count":1}],"type":"LOCAL"},"deploy":{"deployers":[{"type":"HELM","count":1}],"cluster":"MINIKUBE"}}}}}}
{"result":{"timestamp":"2021-01-20T23:56:59.857213Z","event":{
   "terminationEvent":{"status":"Failed","err":{"errCode":"DEPLOY_HELM_VERSION_ERR","message":"creating deployer: Helm not found. Please install helm via https://helm.sh/docs/intro/install.","suggestions":[{"suggestionCode":"INSTALL_HELM","action":"Please install helm via https://helm.sh/docs/intro/install"}]}}}}}
{"result":{"timestamp":"2021-01-20T23:56:59.857219Z"}}

[codecov]

Codecov Report

Merging #5258 (b520ec9) into master (62f4dff) will increase coverage by 0.02%.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master    #5258      +/-   ##
==========================================
+ Coverage   71.90%   71.93%   +0.02%     
==========================================
  Files         388      389       +1     
  Lines       14063    14148      +85     
==========================================
+ Hits        10112    10177      +65     
- Misses       3210     3223      +13     
- Partials      741      748       +7     

Impacted Files	Coverage Δ
pkg/skaffold/errors/errors.go	87.23% <33.33%> (+0.27%)	⬆️
pkg/skaffold/event/event.go	90.78% <100.00%> (+0.02%)	⬆️
pkg/skaffold/docker/image.go	78.13% <0.00%> (-1.40%)	⬇️
pkg/skaffold/schema/defaults/defaults.go	87.42% <0.00%> (-0.08%)	⬇️
cmd/skaffold/app/cmd/flags.go	87.50% <0.00%> (ø)
pkg/skaffold/config/options.go	100.00% <0.00%> (ø)
pkg/skaffold/schema/latest/config.go	58.82% <0.00%> (ø)
pkg/skaffold/runner/generate_pipeline.go	0.00% <0.00%> (ø)
cmd/skaffold/app/cmd/parse_config.go	73.49% <0.00%> (ø)
pkg/skaffold/schema/profiles.go	89.61% <0.00%> (+0.13%)	⬆️
... and 3 more

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[briandealwis]

The TestDebug/helm is #5249 which should be fixed by #5262.

[briandealwis]

Aside: it doesn't seem that logEntry needs to be a pointer?

[gsquared94]

lgtm!