Add support for configuring a Network Policy

[gramidt]

Today, Network Policies must be configured out of band from the chart; however, the chart has access to all necessary data to template them. With this addition, customers that utilize a CNI that supports Network Policies, this will add an additional layer of security out of the box.

[gramidt]

@troytop @wfernandes - This would be a good first contribution to the chart. 🚀