feat: addon rss forwarder

[aumer-amr]

New addon that can be installed, that will post commits from the template into a discord channel. This allows people using the template to be notified and stay up-to-date.

Some notes:

• I chose default namespace for now, I thought about either monitoring or kube-system. Let me know your thoughts.
• Since there is no http server available I disabled all probes, ingress, and service.
• Right now only discord is supported, but the tool itself supports slack, and custom. I just didn't had the time to make this work yet, with how this is currently setup.

Resources of running this app is very low, resource values in helmrelease come from goldilock from my own cluster.

NAME                                             CPU(cores)   MEMORY(bytes)            
rss-forwarder-5f65cc7f49-7hsrf                   0m           22Mi

Example:

• Draft PR since I've not tested this yet outside my own lab which looks a bit different. Will remove draft after testing successfully.

[onedr0p]

@aumer-amr you also need to update the kustomization file here

https://github.com/onedr0p/flux-cluster-template/blob/main/bootstrap/templates/kubernetes/apps/default/kustomization.yaml.j2

[aumer-amr]

@aumer-amr you also need to update the kustomization file here

https://github.com/onedr0p/flux-cluster-template/blob/main/bootstrap/templates/kubernetes/apps/default/kustomization.yaml.j2

Added!