multi: use the "errors" package everywhere

Replace all usages of the "github.com/go-errors/errors" and
"github.com/pkg/errors" packages with the standard lib's "errors"
package. This ensures that error wrapping and `errors.Is` checks will
work as expected.

lnwire/lnwire.go

@@ -3,6 +3,7 @@ package lnwire
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"image/color"
 	"io"
@@ -13,7 +14,6 @@ import (
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/tor"
 )