[CI] push forgejo branches to the specified destination

(cherry picked from commit 22abd100cb)
(cherry picked from commit 4e2c30cb5b)
(cherry picked from commit 1ddc08747c)
(cherry picked from commit ba3df01314)
(cherry picked from commit 644f7cb733)

.forgejo/workflows/mirror.yml

@@ -0,0 +1,25 @@
+name: mirror
+
+on:
+  push:
+    branches:
+      - 'forgejo'
+      - 'v*/forgejo'
+
+jobs:
+  mirror:
+    if: ${{ secrets.MIRROR_TOKEN != '' }}
+    runs-on: docker
+    container:
+      image: 'docker.io/node:20-bookworm'
+    steps:
+      - name: git push {v*/,}forgejo
+        run: |
+          git init --bare .
+          git remote add origin ${{ env.GITHUB_SERVER_URL }}/${{ env.GITHUB_REPOSITORY }}
+          git fetch origin refs/heads/forgejo:refs/mirror/forgejo
+          git ls-remote origin refs/heads/v*/forgejo | while read sha full_ref ; do
+            ref=${full_ref#refs/heads/}
+            git fetch origin $full_ref:refs/mirror/$ref
+          done
+          git push --force https://any:${{ secrets.MIRROR_TOKEN }}@${{ vars.MIRROR_DESTINATION }} refs/mirror/*:refs/heads/*