FORMAT: use jsonnet for templating

* add jsonnet templates
* rewrite all charts to jsonnet

_templates/argo_app.template

@@ -0,0 +1,18 @@
+# vim:ft=jsonnet:
+local base = import "argo_base.template";
+
+base + {
+	repo:: error "repo must be defined",
+	version:: error "version must be defined",
+	path:: error "path must be defined",
+	recursive:: true,
+
+	spec+: {
+		source: {
+			repoURL: $.repo,
+			path: $.path,
+			targetRevision: $.version,
+			directory: { recurse: $.recursive },
+		}
+	}
+}