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/samples/_v1_onepassworditem.yaml

@@ -0,0 +1,6 @@
+apiVersion: onepassword.com/v1
+kind: OnePasswordItem
+metadata:
+  name: onepassworditem-sample
+spec:
+  # TODO(user): Add fields here

config/samples/kustomization.yaml

@@ -0,0 +1,4 @@
+## Append samples you want in your CSV to this file as resources ##
+resources:
+- _v1_onepassworditem.yaml
+#+kubebuilder:scaffold:manifestskustomizesamples