fix: allow quotes on base image tags in Dockerfiles

[nkubala]

Fixes: #7026

Description

Previously, our logic to remove quotes on base images just removed leading/trailing quotes, which was fine for strings like FROM "scratch" but failed with strings like FROM golang:"1.15", which is a valid image reference. This change uses strings.ReplaceAll instead of strings.TrimFunc which should fix this issue.

[codecov]

Codecov Report

Merging #7027 (295babe) into main (290280e) will decrease coverage by 1.66%.
The diff coverage is 56.96%.

@@            Coverage Diff             @@
##             main    #7027      +/-   ##
==========================================
- Coverage   70.48%   68.82%   -1.67%     
==========================================
  Files         515      554      +39     
  Lines       23150    25751    +2601     
==========================================
+ Hits        16317    17722    +1405     
- Misses       5776     6826    +1050     
- Partials     1057     1203     +146     

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/deploy.go	52.00% <ø> (-1.85%)	⬇️
cmd/skaffold/app/cmd/dev.go	84.61% <0.00%> (ø)
cmd/skaffold/app/cmd/render.go	36.66% <0.00%> (-4.72%)	⬇️
cmd/skaffold/skaffold.go	0.00% <0.00%> (ø)
cmd/skaffold/app/cmd/inspect_tests.go	62.50% <14.28%> (-1.14%)	⬇️
cmd/skaffold/app/cmd/lsp.go	28.12% <28.12%> (ø)
cmd/skaffold/app/cmd/fix.go	68.85% <40.00%> (-7.62%)	⬇️
cmd/skaffold/app/cmd/lint.go	42.85% <42.85%> (ø)
cmd/skaffold/app/cmd/find_configs.go	48.88% <50.00%> (+0.24%)	⬆️
cmd/skaffold/app/skaffold.go	76.19% <70.00%> (-8.43%)	⬇️
... and 182 more

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[aaron-prindle]

LGTM