Import minecraft-server chart for Fleet migration stage 1 (java8 line)

Imports the chart from cluster-config functionally unchanged, wires it into
the publish/validate/install-test pipelines and publishes it as the first of
three Java lines (0.4.0+upjava8).

The only deviation from the source chart is the chart-global scaleDown flag
plus a server.replicas value, following the satisfactory pattern: two of the
three servers stand at 0 replicas in the cluster, which the chart could not
express, and Fleet would otherwise start them on reconcile. The default
(scaleDown: false) still renders replicas: 1, so the rendering of the running
server is unchanged - verified byte-identical against the three real values
files for all three Java lines.

Known deficiencies (hardening, probes, naming scheme, hardcoded values,
missing icon, the misleading mc-router auto-discovery annotations) are left
untouched on purpose and are scheduled for stage 2.

minecraft-server/templates/mc-server-service.yaml

@@ -0,0 +1,25 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ .Release.Name }}-service
+  {{- if .Values.mcRouterIntegration.enabled }}
+  annotations:
+    "mc-router.itzg.me/externalServerName": "{{ .Values.mcRouterIntegration.domain }}"
+  {{- end }}
+spec:
+  selector:
+    app: {{ .Release.Name }}-server-deployment
+  {{- if .Values.mcRouterIntegration.enabled }}
+  ports:
+    - name: mc-port
+      port: 25565
+      targetPort: 25565
+  type: ClusterIP
+  {{- else }}
+  ports:
+    - nodePort: {{ .Values.server.outwardPort }}
+      port: 25565
+      targetPort: 25565
+  type: NodePort
+  {{- end }}
+