Support passing additional CLI flags to docker build

[nkubala]

Fixes: #5638

Description

This change introduces a new config field, build.artifacts.docker.cliFlags, which allows users to send arbitrary flags to the Docker CLI when performing a build. Existing natively-supported flags will be left untouched to preserve backwards compatibility, but we should probably refrain from adding any additional flags via fields in the DockerArtifact type.

[codecov]

Codecov Report

Merging #6343 (e204794) into main (47e12af) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #6343      +/-   ##
==========================================
- Coverage   70.45%   70.43%   -0.02%     
==========================================
  Files         498      498              
  Lines       22539    22540       +1     
==========================================
- Hits        15879    15877       -2     
- Misses       5635     5636       +1     
- Partials     1025     1027       +2     

Impacted Files	Coverage Δ
pkg/skaffold/schema/latest/v1/config.go	62.16% <ø> (ø)
pkg/skaffold/docker/image.go	65.56% <100.00%> (-0.89%)	⬇️
pkg/skaffold/docker/parse.go	87.39% <0.00%> (-0.85%)	⬇️
pkg/skaffold/util/tar.go	65.51% <0.00%> (+2.29%)	⬆️

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