Add snappass to the cluster

This change is surprisingly tricky and needed some temporary
workarounds. First, there is no "official" snappass helm chart but I
found one, which does the job and looked good enough. The other problem
is the missing "official" image of snappass. The helm-chart used a
customized image which I didn't want to use, therefore I had to rebuild
a brand new image quickly. This new image is unfortunately not bound to
any repository or pipeline yet, which means that this change needs some
trust for the moment until I've set up the needed repo and CI
structures.

Reference: https://github.com/lmacka/helm-snappass/tree/main
Reference: https://github.com/pinterest/snappass

README.adoc

@@ -176,6 +176,7 @@ You can restrict playbook scope to specific areas using `--tags`.
 `cert-manager`:: Apply changes to the cert-manager including support for `Let's Encrypt`
 `gitea`:: Apply changes to gitea
 `concourse`:: Apply changes to concourse
+`snappass`:: Apply changes to snappass
 
 == Scaling the Cluster