Use 'kubectl' instead of 'tkn' for tree, some minor refactoring

[evidolob]

This PR increase Tekton tree loading speed. Also now Tekton tree use only kubectl to get data for nodes.
Also it add better update tree when pipelinerun is running.

Demo:

Fix: #240
Fix: #239

[codecov-io]

Codecov Report

Merging #255 into master will decrease coverage by 1.13%.
The diff coverage is 79.20%.

@@            Coverage Diff             @@
##           master     #255      +/-   ##
==========================================
- Coverage   71.18%   70.04%   -1.14%     
==========================================
  Files          38       38              
  Lines        2391     2357      -34     
  Branches      405      402       -3     
==========================================
- Hits         1702     1651      -51     
- Misses        689      706      +17     

Impacted Files	Coverage Δ
src/tekton/pipelinerun.ts	100.00% <ø> (ø)
src/kubectl.ts	12.82% <33.33%> (ø)
src/util/tektonresources.virtualfs.ts	83.67% <50.00%> (-0.17%)	⬇️
src/cli.ts	67.21% <65.00%> (-9.35%)	⬇️
src/tkn.ts	75.62% <82.25%> (-3.60%)	⬇️
src/kubernetes.ts	100.00% <100.00%> (ø)
src/pipeline/pipelineExplorer.ts	64.28% <100.00%> (+0.64%)	⬆️
src/tekton/pipeline.ts	35.60% <100.00%> (ø)
src/tekton/tektonitem.ts	91.30% <100.00%> (ø)
src/tools.ts	94.56% <100.00%> (ø)
... and 3 more

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[sudhirverma]

And also I get the error while automatic refreshing the tree

[evidolob]

And also I get the error while automatic refreshing the tree

@sudhirverma I don't see that error, can you share the pipeline?

[sudhirverma]

I think we should refresh the separate node of taskRun as we are refreshing the taskRun under pipelineRun.

[evidolob]

@sudhirverma That should be fixed.