[release/9.0-rc1] Add workflow file for interbranch merging (#106614)

Co-authored-by: Farhad Alizada <[email protected]>

Author: f-alizada

.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