Preserve formatting in Helm values files

[grahamalama]

Welp, I spent quite some time writing this PR to preserve formatting in Helm values files only to discover that there was already some activity in this area, namely #1039 and this branch referenced in that PR.

You can consider this another implementation and maybe decide between the two approaches. There's still more polish I could add, but since I discovered #1039, I thought I'd get this PR up to see if I should keep working on it.

Whether this PR or #1039, it'd be nice to get this general feature of preserving the formatting of Helm values files in.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 83.83234% with 27 lines in your changes missing coverage. Please review.

Project coverage is 62.74%. Comparing base (889af4b) to head (219b67a).

Files with missing lines	Patch %	Lines
pkg/argocd/update.go	83.83%	19 Missing and 8 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1166      +/-   ##
==========================================
- Coverage   63.27%   62.74%   -0.53%     
==========================================
  Files          15       15              
  Lines        2358     2365       +7     
==========================================
- Hits         1492     1484       -8     
- Misses        771      782      +11     
- Partials       95       99       +4     

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[chengfang]

Thanks for the contribution, @grahamalama. PRs #1055 and #1062, based on #1039, were merged and included in v0.16.0.

[grahamalama]

@chengfang ahh I see. So it seems the final version of the formatting changes you mentioned do not use goccy/go-yaml? One consequence of this is that blank lines are not preserved. I've also noticed that image updater (whether through the yaml library or our logic) enforces this opinionated formatting of array items:

array:
- item

vs something like:

array:
  - item

goccy/go-yaml seems to handle both of these things, so I see some benefit of adopting that library as it would lead to overall less noisy diffs when applying updates.

What should I do with this PR? I'm sure it's not desirable to have 2 different yaml libraries in use simultaneously in the project, but if using goccy/go-yaml is something you want to consider further, I can continue working on this PR so that we switch everything over to goccy/go-yaml (or maybe create a separate follow-on PR to handle that). What do you think?

[bewinsnw]

@grahamalama just noticed this one, I wrote a couple of the PRs mentioned above. The indentation of sequences was a deliberate choice in goyaml v3: see go-yaml/yaml#661 and the many, many related discussions. Partly this goes back to, IIRC, goyaml having jumped the other way in v2, breaking the formatting used in k8s, which then led to the entire k8s ecosystem relying on a fork of goyaml to avoid - you guessed it, noisy diffs.