Add phase to status

[nakamasato]

Currently, only conditions is available. I want to know if it's ready or not.

kubectl get mysqluser -o yaml nakamasato
apiVersion: mysql.nakamasato.com/v1alpha1
kind: MySQLUser
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"mysql.nakamasato.com/v1alpha1","kind":"MySQLUser","metadata":{"annotations":{},"name":"nakamasato","namespace":"default"},"spec":{"mysqlName":"mysql-sample"}}
  creationTimestamp: "2021-10-07T01:04:27Z"
  finalizers:
  - mysqluser.nakamasato.com/finalizer
  generation: 1
  name: nakamasato
  namespace: default
  resourceVersion: "42177"
  uid: 025e7a2b-9a17-44ae-b6cb-713b58d8be45
spec:
  host: '%'
  mysqlName: mysql-sample
status:
  conditions:
  - lastTransitionTime: "2021-10-07T01:04:28Z"
    message: 'driver: bad connection'
    observedGeneration: 1
    reason: LastReconcileCycleFailed
    status: "True"
    type: ReconcileError
  - lastTransitionTime: "2021-10-07T01:04:29Z"
    message: ""
    observedGeneration: 1
    reason: LastReconcileCycleSucceded
    status: "True"
    type: ReconcileSuccess

[nakamasato]

Related to #17