feat: add network policies to restrict traffic flow between argocd components

[alexmt]

Signed-off-by: Alexander Matyushentsev AMatyushentsev@gmail.com

PR adds ingress rules that limits which Argo CD components can talk to each other.

• Both HA and non-HA manifests were tested on GKE cluster.

[codecov]

Codecov Report

Merging #6156 (7a9aef6) into master (deac72f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #6156   +/-   ##
=======================================
  Coverage   41.13%   41.13%           
=======================================
  Files         147      147           
  Lines       19956    19956           
=======================================
  Hits         8208     8208           
  Misses      10620    10620           
  Partials     1128     1128           

Impacted Files	Coverage Δ
util/settings/settings.go	46.75% <0.00%> (ø)

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