Remove support for Kustomize 1. Closes #1573

[alexec]

No description provided.

[codecov]

Codecov Report

Merging #2077 into master will decrease coverage by 0.34%.
The diff coverage is 63.15%.

@@            Coverage Diff             @@
##           master    #2077      +/-   ##
==========================================
- Coverage   35.89%   35.55%   -0.35%     
==========================================
  Files          88       88              
  Lines       12908    12827      -81     
==========================================
- Hits         4633     4560      -73     
- Misses       7636     7639       +3     
+ Partials      639      628      -11

Impacted Files	Coverage Δ
reposerver/repository/repository.go	47.82% <100%> (-0.68%)	⬇️
util/kustomize/kustomize.go	73.68% <58.82%> (+5.62%)	⬆️
util/jwt/jwt.go	24.39% <0%> (-37.43%)	⬇️
server/project/project.go	58.52% <0%> (-2.72%)	⬇️
controller/appcontroller.go	40.33% <0%> (-1.37%)	⬇️
cmd/argocd/commands/app.go	0.74% <0%> (ø)	⬆️

---

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[codecov]

Codecov Report

Merging #2077 into master will decrease coverage by 0.04%.
The diff coverage is 63.15%.

@@            Coverage Diff             @@
##           master    #2077      +/-   ##
==========================================
- Coverage   35.66%   35.62%   -0.05%     
==========================================
  Files          88       88              
  Lines       12881    12827      -54     
==========================================
- Hits         4594     4569      -25     
+ Misses       7652     7626      -26     
+ Partials      635      632       -3

Impacted Files	Coverage Δ
reposerver/repository/repository.go	47.82% <100%> (-0.68%)	⬇️
util/kustomize/kustomize.go	73.68% <58.82%> (+5.15%)	⬆️
controller/appcontroller.go	41.7% <0%> (+1.36%)	⬆️

---

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[alexmt]

LGTM. Please address one comment before merging