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/crypto/rsa_fingerpting_test.go

@@ -0,0 +1,26 @@
+package crypto
+
+import (
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"testing"
+)
+
+func TestRSAFingerprint(t *testing.T) {
+	testKey := []byte(`-----BEGIN PUBLIC KEY-----
+MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCJhOrkbrOi7/fFQRN2+8W5+Inx
+bdxo7XH5DDKgFvXPDDe8cQINO3/kFat7KlpC2n2sS8ApZQkmREANg0XpImL9lCHB
+v1FgQmL0xtnaURKo7FzaoaL4jCf5556NQr1th9F3oeN67mR4+BF0vPP9Gu6GY5Z1
+BSqi+FEREW/2aWSgSwIDAQAB
+-----END PUBLIC KEY-----`)
+	b, _ := pem.Decode(testKey)
+	keyParsed, err := x509.ParsePKIXPublicKey(b.Bytes)
+	if err != nil {
+		t.Fatal(err)
+	}
+	key := keyParsed.(*rsa.PublicKey)
+	if RSAFingerprint(key) != 1914007313702140277 {
+		t.Fatal(RSAFingerprint(key))
+	}
+}