DuckDB test to ensure FFI doesn't crash on simple query (#7147)

* test_duckdb_ffi

* build dev duckdb lib

* cache

.github/workflows/backend-test.yml

@@ -67,13 +67,21 @@ jobs:
       - name: Substitute EE code (EE logic is behind feature flag)
         run: |
           ./substitute_ee_code.sh --copy --dir ./windmill-ee-private
+      - name: Cache DuckDB FFI module build
+        uses: actions/cache@v3
+        with:
+          path: ./backend/windmill-duckdb-ffi-internal/target
+          key: ${{ runner.os }}-duckdb-ffi-${{ hashFiles('./backend/windmill-duckdb-ffi-internal/src/**/*.rs', './backend/windmill-duckdb-ffi-internal/Cargo.toml', './backend/windmill-duckdb-ffi-internal/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-duckdb-ffi-
       - name: cargo test
         timeout-minutes: 16
         run: deno --version && bun -v && go version && python3 --version &&
+          cd windmill-duckdb-ffi-internal && ./build_dev.sh && cd .. &&
           SQLX_OFFLINE=true
           DATABASE_URL=postgres://postgres:changeme@localhost:5432/windmill
           DISABLE_EMBEDDING=true RUST_LOG=info RUST_LOG_STYLE=never
           DENO_PATH=$(which deno) BUN_PATH=$(which bun) GO_PATH=$(which go)
           UV_PATH=$(which uv) cargo test --features
-          enterprise,deno_core,license,python,rust,scoped_cache,private --all --
+          enterprise,deno_core,license,python,duckdb,rust,scoped_cache,private --all --
           --nocapture