move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/bin/string_test.go

@@ -0,0 +1,65 @@
+package bin
+
+import (
+	"bytes"
+	"io"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestStringDecodeEncode(t *testing.T) {
+	t.Run("Valid", func(t *testing.T) {
+		a := require.New(t)
+
+		for _, s := range []string{
+			strings.Repeat("abcd", 100),
+			strings.Repeat("abc", 102),
+			strings.Repeat("de", 103),
+			strings.Repeat("z", 104),
+			strings.Repeat("b", 105),
+			"foo",
+			"b",
+			"ba",
+			"what are you doing?",
+			"кек",
+			strings.Repeat("a", 253),
+		} {
+			buf := encodeString(nil, s)
+			a.True(len(buf)%4 == 0, "bad align")
+
+			n, v, err := decodeString(buf)
+			a.NoError(err)
+			a.Equal(s, v)
+			a.NotZero(n, "zero bytes read return")
+		}
+	})
+	t.Run("ErrUnexpectedEOF", func(t *testing.T) {
+		a := require.New(t)
+
+		_, _, err := decodeString(nil)
+		a.ErrorIs(err, io.ErrUnexpectedEOF)
+
+		_, _, err = decodeString([]byte{firstLongStringByte})
+		a.ErrorIs(err, io.ErrUnexpectedEOF)
+
+		_, _, err = decodeString([]byte{firstLongStringByte, 0, 0, 255, 0})
+		a.ErrorIs(err, io.ErrUnexpectedEOF)
+
+		_, _, err = decodeString(encodeString(nil, "foo bar")[:2])
+		a.ErrorIs(err, io.ErrUnexpectedEOF)
+
+		_, _, err = decodeString(encodeString(nil, strings.Repeat("b", 105))[:10])
+		a.ErrorIs(err, io.ErrUnexpectedEOF)
+	})
+	t.Run("InvalidLength", func(t *testing.T) {
+		a := require.New(t)
+
+		_, _, err := decodeString(bytes.Repeat([]byte{255}, 256))
+		var e *InvalidLengthError
+		a.ErrorAs(err, &e)
+		a.Equal("string", e.Where)
+		a.Contains(e.Error(), "string")
+	})
+}