Allow all list based config to be assigned dictionaries

[sunu]

As a continuation of #843, allow more pod properties to be defined as dictionaries for easy overriding.

Adds dictionary support for init_containers, extra_containers, tolerations, node_affinity_preferred, node_affinity_required, pod_affinity_preferred, pod_affinity_required, pod_anti_affinity_preferred and pod_anti_affinity_required

[yuvipanda]

Thank you very much for adding the detailed tests, @sunu!

[consideRatio]

Nice coverage!!

With the trivial exception of storage_access_modes, which is just a list of strings where assignment as dicts probably isn't helpful, this PR covered all list based config! I updated the PR title to capture this a bit better now that I'm to generate a changelog.