flux-operator: Add `extraEnvs` and `hostNetwork` options

[kingdonb]

Building on #10

Helm chart: add extraEnvs array option (597e086a877ee9f2c89e7f773382ce0045921ac8)

I am testing this over at:

https://github.com/kingdonb/cozystack/tree/flux-operator

The cozystack installer has a way of bundling Helm charts internally so it has been relatively easy to verify this chart and check it does what we need 🌮

Testing also here: https://github.com/kingdonb/cozystack-talm-demo

[kingdonb]

OK, the suggested changes should be in order now 🙇