Use file filters action instead of Github's files filter (#24877)

Inspired by
https://github.com/go-gitea/gitea/pull/24530#issuecomment-1558815301

This PR use a file filter action to do different CI jobs according
changed files types. All types are defined in
`.github/file-filters.yml`. Now there are 4 types, `docs`, `backend`,
`frontend` and `build`. Then if a PR only changed docs files, those CI
jobs which passed the conditions will run, and other types are also like
this.

---------

Co-authored-by: silverwind <me@silverwind.io>

.github/workflows/files-changed.yml

@@ -0,0 +1,32 @@
+name: files changed
+
+on:
+  workflow_call:
+    outputs:
+      docs:
+        description: "whether docs files changed"
+        value: ${{ jobs.files-changed.outputs.docs }}
+      backend:
+        description: "whether backend files changed"
+        value: ${{ jobs.files-changed.outputs.backend }}
+      frontend:
+        description: "whether frontend files changed"
+        value: ${{ jobs.files-changed.outputs.frontend }}
+
+jobs:
+  files-changed:
+    name: detect which files changed
+    runs-on: ubuntu-latest
+    timeout-minutes: 3
+    # Map a step output to a job output
+    outputs:
+      docs: ${{ steps.changes.outputs.docs }}
+      backend: ${{ steps.changes.outputs.backend }}
+      frontend: ${{ steps.changes.outputs.frontend }}
+    steps:
+      - uses: actions/checkout@v3
+      - name: Check for backend file changes
+        uses: dorny/paths-filter@v2
+        id: changes
+        with:
+          filters: .github/file-filters.yml