Add automatic backup PVC creation with create_backup_pvc option (#2097)

When users specify a custom backup_pvc name, the operator now
automatically creates the PVC instead of failing with
"does not exist, please create this pvc first."

Changes:
- Add create_backup_pvc variable (default: true) to backup defaults
- Update error condition to check create_backup_pvc before failing
- Update PVC creation condition to include create_backup_pvc
- Add create_backup_pvc field to AWXBackup CRD

Users who want the previous behavior can set create_backup_pvc: false.

config/crd/bases/awx.ansible.com_awxbackups.yaml

@@ -51,6 +51,10 @@ spec:
               backup_pvc:
                 description: Name of the backup PVC
                 type: string
+              create_backup_pvc:
+                description: If true (default), automatically create the backup PVC if it does not exist
+                type: boolean
+                default: true
               backup_pvc_namespace:
                 description: (Deprecated) Namespace the PVC is in
                 type: string