Samba chart: security hardening, configurable node ports, values cleanup

- Add securityContext.pod/container values with hardened defaults; the
  dockur/samba image requires root and a writable root filesystem, so the
  remaining deviations from the baseline are documented in values.yaml
  (caps reduced to CHOWN, DAC_OVERRIDE, FOWNER, NET_BIND_SERVICE, SETGID,
  SETUID; allowPrivilegeEscalation: false)
- Make the NodePorts configurable (samba.smbNodePort/netbiosNodePort,
  defaults 30445/30139 as published before)
- Rename secrets.sambaUsersRef to secrets.sambaUsersSecretRef (breaking)
- Rename the ConfigMap from -config-cfm to -configmap
- Add the tpl-rendered env value convention (value, secretKeyRef,
  configMapKeyRef forms)
- Fix the CI users.conf fixture to the username:uid:groupname:gid:password
  format the pinned image actually parses
- Bump chart to 4.0.0+up4.23.10

Part of #32

samba/templates/samba-config.configmap.yaml

@@ -1,7 +1,7 @@
 apiVersion: v1
 kind: ConfigMap
 metadata:
-  name: {{ .Release.Name }}-{{ .Chart.Name }}-config-cfm
+  name: {{ .Release.Name }}-{{ .Chart.Name }}-configmap
 data:
   smb.conf: |-
     [global]