feat: Add ability to input a completely custom agent configuration to chart

[hawksight]

Currently the config section is written to be helpful and auto template the required yaml based on either default or a list of resources. See here.

# Configuration section for the agent itself
config:
  # Can override the server if using a proxy between agent and Jetstack Secure
  server: "https://platform.jetstack.io"
  # REQUIRED - Your Jetstack Secure Organisation Name
  organisation: ""
  # REQUIRED - Your Jetstack Secure Cluster Name
  cluster: ""
  period: "0h1m0s"
  dataGatherers:
    default: true
    custom: []

If we need to customise this to say namespaces for certain resource, that isn't currently possible.

A better trade of might be to just provide an option to use a customer configmap, or embed the entire config file and ignore the presets.