Provide a list of alternate DNS names for the genSignedCert function

[ToxicWar]

Small fix for the issue in k8s 1.19+

x509: certificate relies on legacy Common Name field, use SANs or temporarily enable Common Name matching with GODEBUG=x509ignoreCN=0

Issue related to new Go version: https://v1-19.docs.kubernetes.io/docs/setup/release/notes/

The deprecated, legacy behavior of treating the CommonName field on X.509 serving certificates as a host name when no Subject Alternative Names are present is now disabled by default. It can be temporarily re-enabled by adding the value x509ignoreCN=0 to the GODEBUG environment variable. (#93264, @justaugustus) [SIG API Machinery, Auth, CLI, Cloud Provider, Cluster Lifecycle, Instrumentation, Network, Node, Release, Scalability, Storage and Testing]

Before:

After:

[tsandall]

@angelbarrera92 can you PTAL? Thanks!

[angelbarrera92]

Yep, it looks good to me.
Reference at the helm docs: https://helm.sh/docs/chart_template_guide/function_list/#gensignedcert

[angelbarrera92]

Maybe @phisco wants to review it too?

[phisco]

LGTM