Add PR membership check [DI-336] (#679)

Follow-up from
#674
Add PR author check to block external PRs

---------

Co-authored-by: Jack Green <[email protected]>

Author: nishaatr

.github/workflows/builder.yaml

@@ -4,9 +4,28 @@ on:
   pull_request_target:
 
 jobs:
+  check_for_membership:
+    runs-on: ubuntu-latest
+    name: Check PR author membership
+    outputs:
+      check-result: ${{ steps.composite.outputs.check-result }}
+    steps: 
+      - name: Action for membership check
+        id: composite
+        uses: hazelcast/hazelcast-tpm/membership@main
+        with:
+          organization-name: 'hazelcast'
+          member-name: ${{ github.actor }}
+          token: ${{ secrets.GH_TOKEN }}
   pr-builder:
     runs-on: ubuntu-latest
+    needs: check_for_membership
     steps:
+      - name: Detect untrusted community PR
+        if: ${{ needs.check_for_membership.outputs.check-result == 'false' }}
+        run: |
+          echo "::error::ERROR: Untrusted external PR. Must be reviewed and executed by Hazelcast" 1>&2;
+          exit 1
       - name: Checkout Code
         uses: actions/checkout@v4
       - name: Set up Java