Make creating the secret optional

[gaima8]

Same as https://github.com/purestorage/helm-charts/pull/258 but for the newer release.

My aim is to have the flux helm-controller install the chart, and it's impractical to pass the API tokens securely for the chart to create the secret. A sealed-secret solves the problem of getting the values in but the chart will at best overwrite the unsealed secret.

I am very much open to ideas on how to handle the validation of arrays better.

[sdodsley]

@Pure-AdamuKaapan Is this change going to mess up the helm schema?

[Pure-AdamuKaapan]

@sdodsley I think this would make it so that arrays is no longer required (obviously). I think this would still validate that the array structs are well formed if they're there but we should confirm that locally to be sure

[gaima8]

Hi, requested changes to the README made.