Hide minikube detection behind flag

[gsquared94]

Add flag --detect-minikube which is false by default.

[codecov]

Codecov Report

Merging #4745 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4745   +/-   ##
=======================================
  Coverage   73.41%   73.42%           
=======================================
  Files         345      345           
  Lines       13750    13755    +5     
=======================================
+ Hits        10095    10100    +5     
  Misses       3022     3022           
  Partials      633      633           

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/flags.go	86.36% <ø> (ø)
pkg/skaffold/config/options.go	100.00% <ø> (ø)
pkg/skaffold/build/local/types.go	86.66% <100.00%> (ø)
pkg/skaffold/config/util.go	69.94% <100.00%> (+0.63%)	⬆️
pkg/skaffold/runner/runcontext/context.go	86.07% <100.00%> (+0.17%)	⬆️

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[nkubala]

we can probably remove this flag and enable this by default in the v1.15.0 release.