feat: add toYaml and fromYaml to functions map

[jasondamour]

Adds toYaml and fromYaml functions from helm src

[jasondamour]

Hiya @norwoodj , can you approve my CI when you get time? Thanks

[johanneskastl]

I would love to see those functions, as they were used a lot by the k8s-at-home guys in their charts (which are deprecated, so I forked some and noticed the missing functions...)

[gabe565]

This would be amazing. There's also a PR to add this in Masterminds/sprig#360

[jasondamour]

@Nepo26 Need anything from me to move this?

[Nepo26]

Honestly, only chart examples in the example-charts folder and test cases for automated testing. Any question you may ping me.

[norwoodj]

@jasondamour Agreeing with @Nepo26, if you add an example chart that uses these, and a test case, we'll merge.

[ebuildy]

hello, this look fantastic, may I help?

[ebuildy]

I love you :-)

I can add an example and some tests, here my readme_template, to display storage class:

{{ $values := (.Files.Get "values.yaml") | fromYaml }}

## Snapshot classes

| name     | resource group | incremental |
|----------|----------------|-------------|
{{- range $name, $spec := $values.volumeSnapshotClass }}
{{- range $parameterIncr := list "true" "false" }}
| {{ $name }}{{- if eq $parameterIncr "true" -}}-incr{{- end }} | {{ $parameterIncr }} | {{ $spec.parameters.resourceGroup | default "" }} |
{{- end }}
{{- end }}

This work like a charm!