fix: plugin panic while watching progress

[jessesuen]

Resolves #1747

Fixes a panic introduced in v1.1.0 plugin which closed a channel prematurely while the sender (view controller) was still sending on it. This change prevents this by deferring the channel close, and also niling out the view controller's callback list when the view controller stops, so that it will not attempt to perform any callbacks when finished.

As part of this fix, I made the plugin less chatty and only showed status changes. Previously, it would print out the phase and message on every rollout change, even if it was the same as before. Example output:

$ kubectl-argo-rollouts status my-rollout -w
Progressing - more replicas need to be updated
Paused - CanaryPauseStep
Progressing - more replicas need to be updated
Progressing - updated replicas are still becoming available
Healthy

Signed-off-by: Jesse Suen [email protected]

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
4.4% Duplication

[codecov]

Codecov Report

Merging #1796 (6964726) into master (f5c229b) will decrease coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1796      +/-   ##
==========================================
- Coverage   82.11%   82.06%   -0.05%     
==========================================
  Files         116      116              
  Lines       16317    16340      +23     
==========================================
+ Hits        13398    13410      +12     
- Misses       2236     2243       +7     
- Partials      683      687       +4     

Impacted Files	Coverage Δ
pkg/kubectl-argo-rollouts/cmd/status/status.go	94.18% <100.00%> (+0.43%)	⬆️
...ctl-argo-rollouts/viewcontroller/viewcontroller.go	70.58% <100.00%> (-1.44%)	⬇️
rollout/trafficrouting/istio/controller.go	50.81% <0.00%> (-1.63%)	⬇️
pkg/kubectl-argo-rollouts/info/rollout_info.go	87.50% <0.00%> (-1.27%)	⬇️
rollout/trafficrouting/istio/istio.go	81.19% <0.00%> (+0.03%)	⬆️

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[rbreeze]

LGTM