multi: freeze graph SQL migration logic

Copy over all the code that the graph SQL migration needs to a
separate folder. This will let us advance the main graph SQL CRUD code
without worrying about changing the sql migration code. It will also let
us change the SQL queries without changing the migration. In this
commit, only the migration logic is "frozen" but in an upcoming commit,
the sqlc queries & models will be frozen too.

graph/db/migration1/test_postgres.go

@@ -0,0 +1,79 @@
+//go:build test_db_postgres && !test_db_sqlite
+
+package migration1
+
+import (
+	"database/sql"
+	"testing"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/lightningnetwork/lnd/sqldb"
+	"github.com/stretchr/testify/require"
+)
+
+// NewTestDB is a helper function that creates a SQLStore backed by a SQL
+// database for testing.
+func NewTestDB(t testing.TB) V1Store {
+	return NewTestDBWithFixture(t, nil)
+}
+
+// NewTestDBFixture creates a new sqldb.TestPgFixture for testing purposes.
+func NewTestDBFixture(t *testing.T) *sqldb.TestPgFixture {
+	pgFixture := sqldb.NewTestPgFixture(
+		t, sqldb.DefaultPostgresFixtureLifetime,
+	)
+	t.Cleanup(func() {
+		pgFixture.TearDown(t)
+	})
+	return pgFixture
+}
+
+// NewTestDBWithFixture is a helper function that creates a SQLStore backed by a
+// SQL database for testing.
+func NewTestDBWithFixture(t testing.TB,
+	pgFixture *sqldb.TestPgFixture) V1Store {
+
+	var querier BatchedSQLQueries
+	if pgFixture == nil {
+		querier = newBatchQuerier(t)
+	} else {
+		querier = newBatchQuerierWithFixture(t, pgFixture)
+	}
+
+	store, err := NewSQLStore(
+		&SQLStoreConfig{
+			ChainHash: *chaincfg.MainNetParams.GenesisHash,
+			QueryCfg:  sqldb.DefaultPostgresConfig(),
+		}, querier,
+	)
+	require.NoError(t, err)
+
+	return store
+}
+
+// newBatchQuerier creates a new BatchedSQLQueries instance for testing
+// using a PostgreSQL database fixture.
+func newBatchQuerier(t testing.TB) BatchedSQLQueries {
+	pgFixture := sqldb.NewTestPgFixture(
+		t, sqldb.DefaultPostgresFixtureLifetime,
+	)
+	t.Cleanup(func() {
+		pgFixture.TearDown(t)
+	})
+
+	return newBatchQuerierWithFixture(t, pgFixture)
+}
+
+// newBatchQuerierWithFixture creates a new BatchedSQLQueries instance for
+// testing using a PostgreSQL database fixture.
+func newBatchQuerierWithFixture(t testing.TB,
+	pgFixture *sqldb.TestPgFixture) BatchedSQLQueries {
+
+	db := sqldb.NewTestPostgresDB(t, pgFixture).BaseDB
+
+	return sqldb.NewTransactionExecutor(
+		db, func(tx *sql.Tx) SQLQueries {
+			return db.WithTx(tx)
+		},
+	)
+}