feat: add utils/dftools, is_quantamental_dataframe function to validate DataFrame structure

src/utils/dftools.rs

@@ -0,0 +1,18 @@
+use polars::prelude::*;
+
+const QDF_IDX_COLUMNS: [&str; 3] = ["real_date", "cid", "xcat"];
+
+/// Check if a DataFrame is a quantamental DataFrame.
+fn is_quantamental_dataframe(df: &DataFrame) -> bool {
+    let columns = df
+        .get_column_names()
+        .iter()
+        .map(|s| s.as_str())
+        .collect::<Vec<&str>>();
+    let has_idx_columns = QDF_IDX_COLUMNS.iter().all(|col| columns.contains(col));
+
+    // check if real_date is date-type
+    let real_date = df.column("real_date").unwrap();
+
+    has_idx_columns
+}