style: apply rustfmt, fix clippy warnings, and minor code cleanup

Reformat Rust code with rustfmt, suppress clippy::too_many_arguments
for Tauri IPC commands, derive Default for AppSettings, fix unused
variable pattern in TableDataView, and add unit tests for utils.

src-tauri/src/commands/schema.rs

@@ -28,10 +28,7 @@ pub async fn list_databases(
     Ok(rows.iter().map(|r| r.get::<String, _>(0)).collect())
 }
 
-pub async fn list_schemas_core(
-    state: &AppState,
-    connection_id: &str,
-) -> TuskResult<Vec<String>> {
+pub async fn list_schemas_core(state: &AppState, connection_id: &str) -> TuskResult<Vec<String>> {
     let pool = state.get_pool(connection_id).await?;
 
     let flavor = state.get_flavor(connection_id).await;
@@ -593,11 +590,13 @@ pub async fn get_schema_erd(
     let mut tables_map: HashMap<String, ErdTable> = HashMap::new();
     for row in &col_rows {
         let table_name: String = row.get(0);
-        let entry = tables_map.entry(table_name.clone()).or_insert_with(|| ErdTable {
-            schema: schema.clone(),
-            name: table_name,
-            columns: Vec::new(),
-        });
+        let entry = tables_map
+            .entry(table_name.clone())
+            .or_insert_with(|| ErdTable {
+                schema: schema.clone(),
+                name: table_name,
+                columns: Vec::new(),
+            });
         entry.columns.push(ErdColumn {
             name: row.get(1),
             data_type: row.get(2),