External contributor auto-draft and dispatch pr-review event type (#20329)

# Introduction

## Auto draft
On external contributor PR creation auto draft it and comment stating
that it needs to be marked as ready for review when it is

## Caveats / future improvement
Lets iterate first but we can imagine future pain points such as:
- Cubic only runs on ready for review PRs
- Expected green ci before turning ready to be review ? ( we could
invoke cubic ourselves )\
- Auto close external contributors draft PR after x duration

## Auto review
Once a PR started to be review or is being synchronized then auto
dispatch auto review

.github/workflows/external-contributor-pr-auto-draft.yaml

@@ -0,0 +1,42 @@
+name: Auto-Draft External PRs
+
+on:
+  pull_request_target:
+    types: [opened]
+
+permissions:
+  pull-requests: write
+
+jobs:
+  convert-to-draft:
+    if: |
+      github.event.pull_request.draft == false &&
+      github.event.pull_request.author_association != 'MEMBER' &&
+      github.event.pull_request.author_association != 'OWNER' &&
+      github.event.pull_request.author_association != 'COLLABORATOR'
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Convert to draft
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR_NODE_ID: ${{ github.event.pull_request.node_id }}
+        run: |
+          gh api graphql -f query="
+            mutation {
+              convertPullRequestToDraft(input: {pullRequestId: \"$PR_NODE_ID\"}) {
+                pullRequest { isDraft }
+              }
+            }
+          "
+
+      - name: Welcome comment
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        run: |
+          gh pr comment "$PR_NUMBER" --repo ${{ github.repository }} --body "👋 Thanks for contributing to Twenty!
+
+          Your PR has been set to draft while you work on it. Once you're done, mark it as **Ready for review** and our automated checks will run.
+
+          Looking forward to your contribution!"