[release/10.0.1xx] Add merge flow configuration for release/10.0 (#1531)

* Add merge flow configuration for release/10.0

This file configures the merge flow for the release branch.

* Add inter-branch merge workflow configuration

* Add backport workflow for PR management

---------

Co-authored-by: Viktor Hofer <[email protected]>

Author: github-actions[bot]

.github/workflows/backport.yml

@@ -0,0 +1,17 @@
+name: Backport PR to branch
+on:
+  issue_comment:
+    types: [created]
+  schedule:
+    # once a day at 13:00 UTC to cleanup old runs
+    - cron: '0 13 * * *'
+
+permissions:
+  contents: write
+  issues: write
+  pull-requests: write
+  actions: write
+
+jobs:
+  backport:
+    uses: dotnet/arcade/.github/workflows/backport-base.yml@main

.github/workflows/inter-branch-merge-flow.yml

@@ -0,0 +1,13 @@
+name: Inter-branch merge workflow
+on:
+  push:
+    branches:
+      - release/**
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  Merge:
+    uses: dotnet/arcade/.github/workflows/inter-branch-merge-base.yml@main

github-merge-flow.jsonc

@@ -0,0 +1,10 @@
+// IMPORTANT: This file is read by the merge flow from main branch only. 
+{
+    "merge-flow-configurations": {
+        // Automate opening PRs to merge release/10.0 to main
+        "release/10.0":{
+            "MergeToBranch": "main",
+            "ExtraSwitches": "-QuietComments"
+        }
+    }
+}