[SL-ONLY] Add workflow to open PR from csa to main after the csa update is completed (#238)

Author: mkardous-silabs

.github/workflows/silabs-open-csa-pr.yaml

@@ -0,0 +1,54 @@
+name: Open PR from csa to main
+
+permissions:
+    contents: write
+    pull-requests: write
+
+on:
+    workflow_run:
+        workflows: ["Daily Sync of the csa branch"]
+        types:
+            - completed
+    workflow_dispatch:
+
+jobs:
+    open-pr:
+        if: ${{ github.event.workflow_run.conclusion == 'success' }}
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v4
+              with:
+                  ref: main
+                  token: ${{secrets.WORKFLOW_TOKEN}}
+
+            - name: Checkout csa
+              run: |
+                  git fetch origin csa:csa
+                  git reset --hard csa
+
+            - name: Create Pull Request
+              uses: peter-evans/create-pull-request@v7
+              with:
+                  branch: automation/update_main
+                  base: main
+                  title: "Sync csa branch with main"
+                  body: |
+                      This PR syncs the csa branch with the main branch.
+
+                      **PR MUST BE MERGED WITH MERGE COMMIT - ADMIN MUST ENABLE THE OPTION**
+                  token: ${{secrets.GITHUB_TOKEN}}
+                  branch-token: ${{secrets.WORKFLOW_TOKEN}}
+                  labels: changing-submodules-on-purpose
+
+            - name: Comment on Pull Request
+              uses: actions/github-script@v7
+              with:
+                  github-token: ${{secrets.GITHUB_TOKEN}}
+                  script: |
+                      const pr_number = context.payload.workflow_run.pull_requests[0].number;
+                      github.issues.createComment({
+                        owner: context.repo.owner,
+                        repo: context.repo.repo,
+                        issue_number: pr_number,
+                        body: "Please merge this PR using **Merge Commit**."
+                      });