Add ACSA config script (#188)

## Purpose
Adds config script to enable ACSA resource sync

## Does this introduce a breaking change?
<!-- Mark one with an "x". -->
```
[ ] Yes
[x] No
```

## Pull Request Type
What kind of change does this Pull Request introduce?

<!-- Please check the one that applies to this PR using "x". -->
```
[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe:
```

Author: dominicbetts

samples/acsa-config/enable-rp-on-arc.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+RG=$(kubectl get connectedclusters -A -o json | jq -r '.items[0].spec.azureResourceId | split("/") | .[4]')
+
+function howto_lookup {
+  echo "Lookup the k8 bridge oid using this command:"
+  echo "  az ad sp list --filter \"appId eq '319f651f-7ddb-4fc6-9857-7aef9250bd05'\" --query '[].id' -o tsv"
+}
+
+if [[ -z "$K8_BRIDGE" ]]; then
+  echo "Error: K8_BRIDGE is not set in env."
+  howto_lookup
+  exit 1
+fi
+
+if [ -z "${RG}" ]; then
+  echo "No Arc cluster found in current kube context"
+fi
+
+set -e
+
+echo "Assigning acsa-rp-role to k8bridge (${K8_BRIDGE})"
+
+kubectl apply -f - <<EOF
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  annotations:
+  labels:
+  name: k8bridge
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: acsa-rp-role
+subjects:
+  - kind: User
+    name: "${K8_BRIDGE}"
+    namespace: azure-arc
+EOF