Add market data backfilling

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

src/types/class.rs

@@ -0,0 +1,12 @@
+use serde::{Deserialize, Serialize};
+use sqlx::Type;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type, Hash)]
+pub enum Class {
+    #[sqlx(rename = "us_equity")]
+    #[serde(rename = "us_equity")]
+    UsEquity,
+    #[sqlx(rename = "crypto")]
+    #[serde(rename = "crypto")]
+    Crypto,
+}