Remove tokio runtime dependency in binder

[TennyZhuang]

Currently, we utilize the FrontendEnv extensively in the risingwave-frontend crate, which complicates and makes testing the binder a tedious task. Creating a FrontendEnv relies on the tokio runtime, requiring all binder tests to initialize a tokio runtime. For example:

    #[tokio::test]
    async fn basic_value() {
        expect_actual_eq(
            create_expect_bound("values(1::int4)"),
            create_actual_bound(
                "values($1::int4)",
                vec![],
                vec![Some("1".into())],
                vec![Format::Text],
            ),
        );
    }

    #[tokio::test]
    async fn default_type() {
        expect_actual_eq(
            create_expect_bound("select '1'"),
            create_actual_bound(
                "select $1",
                vec![],
                vec![Some("1".into())],
                vec![Format::Text],
            ),
        );
    }

Removing tokio::test seems strange, but if we do so, the test will panic.

To create FrontendEnv, we need to initialize a hummock_snapshot_manager and spawn an unpinned background worker.

risingwave/src/frontend/src/scheduler/snapshot.rs

Line 149 in 887655f

tokio::spawn(UnpinWorker::new(meta_client, worker_receiver).run());

The field is definitely useless in the whole binder module, I'd prefer split a BinderEnv from FrontendEnv.

[github-actions]

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