Update helm charts beyond values.yaml

[jeffwidman]

The docker updater for helm charts was hardcoded to "values.yaml".

But we should support the full range of filenames supported in the file fetcher... for example, in the wild we saw this failing to update "arc-values.yaml" because of this hardcoding.

[jeffwidman]

Need tests for the updater to ensure we're processing this full suite of files that we do in the fetcher:

dependabot-core/docker/spec/dependabot/docker/file_fetcher_spec.rb

Lines 273 to 286 in 9b2f675

	matching_filenames = [
	"other-values.yml",
	"other-values.yaml",
	"other_values.yml",
	"other_values.yaml",
	"values.yml",
	"values.yaml",
	"values-other.yml",
	"values-other.yaml",
	"values_other.yml",
	"values_other.yaml",
	"values2.yml",
	"values2.yaml"
	]

[jeffwidman]

I broke the unit tests out separately into #6105 so that it's not blocking merging this code... I'm still learning the Rspec DSL, but since this code is behind a feature flag I'd like to get it live sooner so that if there are other bugs/issues I can see them sooner even while I work through the unit tests. Also so that I can continue to test this code w/o being blocked because other maintainers are offline for Veteran's day.

[jeffwidman]

I manually confirmed this is working against the previously failing repo:

[dependabot-core-dev] ~/dependabot-core $ LOCAL_GITHUB_ACCESS_TOKEN=supersecret bin/dry-run.rb --dir "/manifest_staging/charts/csi-secrets-store-provider-azure" docker jeffwidman/secrets-store-csi-driver-provider-azure --updater-options=kubernetes_updates

...

 => requirements update strategy:
 => updating oss/kubernetes-csi/secrets-store/driver from v1.2.3 to v1.2.4.1

    ± arc-values.yaml
    ~~~
    115c115
    <       tag: v1.2.3
    ---
    >       tag: v1.2.4.1
    128c128
    <         tag: v1.2.3
    ---
    >         tag: v1.2.4.1
    140c140
    <       tag: v1.2.3
    ---
    >       tag: v1.2.4.1
    ~~~

    ± values.yaml
    ~~~
    117c117
    <       tag: v1.2.3
    ---
    >       tag: v1.2.4.1
    130c130
    <         tag: v1.2.3
    ---
    >         tag: v1.2.4.1
    141c141
    <       tag: v1.2.3
    ---
    >       tag: v1.2.4.1
    ~~~
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[jeffwidman]

This has been deployed. I'll finish up the unit tests shortly in the other PR.