core: Fix codegen for rowid alias

We should emit `Column` bytecode for a primary key, unless it is an alias for a rowid.

core/schema.rs

@@ -154,6 +154,13 @@ pub struct Column {
     pub primary_key: bool,
 }
 
+impl Column {
+    pub fn is_rowid_alias(&self) -> bool {
+        self.primary_key && self.ty == Type::Integer
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
 pub enum Type {
     Null,
     Text,