Add custom network policies

Feature Request

Why

We need a way for consumers to be able to add in their own flavors of network policies at the values-level by either establishing a way for them to add the policies at the package level or at the big bang template level.

Gitlab-Runner is one of the packages that currently supports this feature by allowing consumers to add in additional policies via gitlabRunner.values.networkPolicies.additionalPolicies

Proposed Solution

Add /charts/templates/bigbang/networkpolcies/additional-networkpolcies.yaml following this Example and update the values.yaml and README.md to reflect these changes.