implement storage + improve code

server/src/config.rs

@@ -1,5 +1,5 @@
-use rumqttd::Config;
 use serde::Deserialize;
+use rumqttd::Config;
 
 const CONFIG_PATH: &str = if cfg!(debug_assertions) {
     "server/config.toml"
@@ -7,8 +7,15 @@ const CONFIG_PATH: &str = if cfg!(debug_assertions) {
     "config.toml"
 };
 
+#[derive(Debug, Deserialize)]
+pub struct StorageConfig {
+    pub sqlite: bool,
+    pub db_path: String,
+}
+
 #[derive(Debug, Deserialize)]
 pub struct Configuration {
+    pub storage: StorageConfig,
     pub mqtt: Config,
 }