chore: add migration that backfills scim user email hashes (#9295)

Author: daveleek

src/migrations/20250211114205-scim-email-hash-backfill.js

@@ -0,0 +1,14 @@
+exports.up = (db, cb) => {
+    db.runSql(`
+        UPDATE users
+        SET email_hash = md5(email::text)
+        WHERE scim_id IS NOT NULL;
+    `, cb);
+  
+  };
+  
+  exports.down = (db, cb) => {
+    cb();
+  };
+  
+