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](https://repo1.dso.mil/big-bang/product/packages/gitlab-runner/-/blob/main/chart/templates/bigbang/networkpolicies/egress-runner-jobs.yaml?ref_type=heads) and update the values.yaml and README.md to reflect these changes.
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