Start work on storing notifications in the database

crates/collab/src/db/tables/notification_kind.rs

@@ -0,0 +1,14 @@
+use sea_orm::entity::prelude::*;
+
+#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+#[sea_orm(table_name = "notification_kinds")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub id: i32,
+    pub name: String,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {}
+
+impl ActiveModelBehavior for ActiveModel {}