refactor: Restructure project layout and clean up dependencies (#30)

This commit introduces a significant reorganization of the project structure to improve maintainability and clarity.

Key changes include:
- Adjusted the directory layout for a more logical module organization.
- Removed unused crate dependencies, reducing the overall project size and potentially speeding up build times.
- Updated import paths and configuration files to reflect the structural changes.

crates/s3select-api/src/server/dbms.rs

@@ -0,0 +1,55 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use async_trait::async_trait;
+
+use crate::{
+    QueryResult,
+    query::{
+        Query,
+        execution::{Output, QueryStateMachineRef},
+        logical_planner::Plan,
+    },
+};
+
+pub struct QueryHandle {
+    query: Query,
+    result: Output,
+}
+
+impl QueryHandle {
+    pub fn new(query: Query, result: Output) -> Self {
+        Self { query, result }
+    }
+
+    pub fn query(&self) -> &Query {
+        &self.query
+    }
+
+    pub fn result(self) -> Output {
+        self.result
+    }
+}
+
+#[async_trait]
+pub trait DatabaseManagerSystem {
+    async fn execute(&self, query: &Query) -> QueryResult<QueryHandle>;
+    async fn build_query_state_machine(&self, query: Query) -> QueryResult<QueryStateMachineRef>;
+    async fn build_logical_plan(&self, query_state_machine: QueryStateMachineRef) -> QueryResult<Option<Plan>>;
+    async fn execute_logical_plan(
+        &self,
+        logical_plan: Plan,
+        query_state_machine: QueryStateMachineRef,
+    ) -> QueryResult<QueryHandle>;
+}

crates/s3select-api/src/server/mod.rs

@@ -0,0 +1,15 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub mod dbms;