Add CLA bot

.github/workflows/cla.yaml

+name: Check CLA
+
+on:
+  issue_comment:
+    types: [created]
+  pull_request_target:
+    types: [opened, closed, synchronize]
+
+jobs:
+  cla:
+    name: Check CLA
+    runs-on: ubuntu-latest
+    steps:
+      - name: CLA Assistant
+        if: (github.event.comment.body == 'recheck' || github.event.comment.body == 'I have read the CLA Document and I hereby sign the CLA') || github.event_name == 'pull_request_target'
+        uses: secondlife-3p/contributor-assistant@v2
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PERSONAL_ACCESS_TOKEN: ${{ secrets.SHARED_CLA_TOKEN }}
+        with:
+          branch: main
+          path-to-document: https://github.com/secondlife/cla/blob/master/CLA.md
+          path-to-signatures: signatures.json
+          remote-organization-name: secondlife
+          remote-repository-name: cla-signatures