antiaffinity rules should allow custom rules

[nvtkaszpir]

Right now there is antiaffinity setting 'soft' and 'hard' but it is hardcoded to the specific entries.
I need more fine-grained affinity rules, such as availability zone i GKE.

So there are two options:

• alter current antiaffinity settings and move them from templates to values.yaml - this is most commonnly used option
• keep it as is and introduce 'custom' which would then use something like antiAffinitySpec as passthrough value

[cgiraldo]

I will go for the first option. Go ahead if you want to provide a PR.