Add gitea as git-server to k8s-cluster

By applying this change the kubernetes cluster gets a gitea-server
setup. Note, that I use a custom-image which I have to automate in
future. The customization is necessary since I use asciidoc very often
and the default-gitea doesn't render these files, so it becomes a bit
cumbersome to read them on the web.

roles/k8s-setup/defaults/main.yml

@@ -1,3 +1,11 @@
 cert_manager_state: present
 cert_manager_version: v1.18.2
 letsencrypt_clusterissuers: {}
+gitea_chart_version: 12.3.0
+gitea_state: present
+gitea_image_rootless: False
+gitea_image_pull_policy: IfNotPresent
+gitea_image: gitea-for-nehrke-info
+gitea_image_tag: latest
+gitea_image_registry: docker.nehrke.info
+