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/rpc/options.go

@@ -0,0 +1,40 @@
+package rpc
+
+import (
+	"time"
+
+	"go.uber.org/zap"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/clock"
+)
+
+// Options of rpc engine.
+type Options struct {
+	RetryInterval time.Duration
+	MaxRetries    int
+	Logger        *zap.Logger
+	Clock         clock.Clock
+	DropHandler   DropHandler
+	OnError       func(error)
+}
+
+func (cfg *Options) setDefaults() {
+	if cfg.RetryInterval == 0 {
+		cfg.RetryInterval = time.Second * 10
+	}
+	if cfg.MaxRetries == 0 {
+		cfg.MaxRetries = 5
+	}
+	if cfg.Logger == nil {
+		cfg.Logger = zap.NewNop()
+	}
+	if cfg.Clock == nil {
+		cfg.Clock = clock.System
+	}
+	if cfg.DropHandler == nil {
+		cfg.DropHandler = NopDrop
+	}
+	if cfg.OnError == nil {
+		cfg.OnError = func(err error) {}
+	}
+}