Proposal: Add extra parameter to helm diff

[PPACI]

kubernetes.core/plugins/modules/helm.py

Line 631 in 318529a

def helmdiff_check(

Using this function, helm diff is used when available. This is a great help!
Though, in some case, it would be useful to add some extra args such as --show-secrets.

I was thinking of adding the content of an environment variable such as `ANSIBLE_HELM_DIFF_EXTRAVARS".

I could take care of writing a pull request with implementation + tests. What do you think?

[PPACI]

Hi
I would like to recomment on this.
I will propose a pull request using the ANSIBLE_HELM_DIFF_EXTRAVARS mechanism.
Let me know if you prefer me to implement this in another way.