Add a dummy yaml file for a separate fmt/lint/typecheck step

This makes debugging the implementation in a PR/branch possible,
without running the entire CI step.

.github/workflows/fmt_lint_typecheck.yaml

@@ -0,0 +1,17 @@
+# Copyright © SixtyFPS GmbH <info@slint.dev>
+# SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
+
+# Run various formatters, linters, and type-checkers (Rust, C++, TypeScript, etc.)
+name: Format, Lint, and type-check
+
+on:
+    workflow_call:
+    workflow_dispatch:
+
+jobs:
+    format_lint_typecheck:
+        runs-on: ubuntu-24.04
+        env:
+            CARGO_INCREMENTAL: false
+        steps:
+            - uses: actions/checkout@v4