ServiceAccounts: Add Service Account Token last used at date (#51446)

* ServiceAccounts Add api key last used at

* ServiceAccounts: LastUpdateAt tests

pkg/services/sqlstore/migrations/apikey_mig.go

@@ -91,4 +91,8 @@ func addApiKeyMigrations(mg *Migrator) {
 
 	mg.AddMigration("set service account foreign key to nil if 0", NewRawSQLMigration(
 		"UPDATE api_key SET service_account_id = NULL WHERE service_account_id = 0;"))
+
+	mg.AddMigration("Add last_used_at to api_key table", NewAddColumnMigration(apiKeyV2, &Column{
+		Name: "last_used_at", Type: DB_DateTime, Nullable: true,
+	}))
 }