Create OnePasswordItem API and controller

Command executed: `operator-sdk create api --version v1 --kind OnePasswordItem --resource --controller`
`--group` flag is skipped because we don't have a group in the previous version of the operator and we want to make things consistent and not bring any breaking changes.

config/rbac/onepassworditem_viewer_role.yaml

@@ -0,0 +1,20 @@
+# permissions for end users to view onepassworditems.
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: onepassworditem-viewer-role
+rules:
+- apiGroups:
+  - onepassword.com
+  resources:
+  - onepassworditems
+  verbs:
+  - get
+  - list
+  - watch
+- apiGroups:
+  - onepassword.com
+  resources:
+  - onepassworditems/status
+  verbs:
+  - get