feat: introduce --output option for "fix" cmd

[ahmetb]

Fixes #6456.

• introduced --output/-o (mut.exclusive with --overwrite)
• add more examples
• add more integration tests

[codecov]

Codecov Report

Merging #6849 (f54e817) into main (290280e) will decrease coverage by 1.35%.
The diff coverage is 61.83%.

@@            Coverage Diff             @@
##             main    #6849      +/-   ##
==========================================
- Coverage   70.48%   69.13%   -1.36%     
==========================================
  Files         515      547      +32     
  Lines       23150    25064    +1914     
==========================================
+ Hits        16317    17327    +1010     
- Misses       5776     6574     +798     
- Partials     1057     1163     +106     

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/flags.go	91.00% <0.00%> (+0.18%)	⬆️
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/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 163 more

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[tejal29]

Testing Notes:

➜  skaffold git:(fix-output) ✗ LOCAL=true make

➜  skaffold git:(fix-output) ✗ cd examples/getting-started

➜  getting-started git:(fix-output) ✗ ../../out/skaffold fix --overwrite -o output.yaml
--overwrite and --output/-o cannot be used together

➜  getting-started git:(fix-output) ✗ ../../out/skaffold fix -o output.yaml 
New config at version skaffold/v2beta26 generated and written to output.yaml

➜  getting-started git:(fix-output) ✗ diff output.yaml skaffold.yaml 
1c1
< apiVersion: skaffold/v2beta26
---
> apiVersion: skaffold/v2beta25
9c9
<     - k8s-*
---
>       - k8s-*
➜  getting-started git:(fix-output) ✗