feat: add first class support for private github repos (#1271)

Signed-off-by: Devin Buhl <devin@buhl.casa>

bootstrap/templates/kubernetes/bootstrap/github-deploy-key.sops.yaml.j2

@@ -0,0 +1,17 @@
+{% if flux.github.private.enabled %}
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: github-deploy-key
+  namespace: flux-system
+stringData:
+  identity: |
+    {% filter indent(width=4, first=False) %}
+    {{ flux.github.private.key }}
+    {%- endfilter %}
+  known_hosts: |
+    github.com ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOMqqnkVzrm0SdG6UOoqKLsabgH5C9okWi0dh2l9GKJl
+    github.com ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBEmKSENjQEezOmxkZMy7opKgwFB9nkt5YRrYMjNuG5N87uRgg6CLrbo5wAdT/y6v0mKV0U2w0WZ2YB/++Tpockg=
+    github.com ssh-rsa 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
+{% endif %}

bootstrap/templates/kubernetes/flux/config/cluster.yaml.j2

@@ -7,7 +7,7 @@ metadata:
 spec:
   interval: 30m
   url: "{{ flux.github.address }}"
-  {% if flux.github.address.startswith('ssh://') %}
+  {% if flux.github.private.enabled %}
   secretRef:
     name: github-deploy-key
   {% endif %}