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/ack.go

@@ -0,0 +1,45 @@
+package rpc
+
+import (
+	"go.uber.org/zap"
+)
+
+// NotifyAcks notifies engine about received acknowledgements.
+func (e *Engine) NotifyAcks(ids []int64) {
+	e.mux.Lock()
+	defer e.mux.Unlock()
+
+	for _, id := range ids {
+		ch, ok := e.ack[id]
+		if !ok {
+			e.log.Debug("Acknowledge callback not set", zap.Int64("msg_id", id))
+			continue
+		}
+
+		close(ch)
+		delete(e.ack, id)
+	}
+}
+
+func (e *Engine) waitAck(id int64) chan struct{} {
+	e.mux.Lock()
+	defer e.mux.Unlock()
+
+	log := e.log.With(zap.Int64("ack_id", id))
+	if c, found := e.ack[id]; found {
+		log.Warn("Ack already registered")
+		return c
+	}
+
+	log.Debug("Waiting for acknowledge")
+	c := make(chan struct{})
+	e.ack[id] = c
+	return c
+}
+
+func (e *Engine) removeAck(id int64) {
+	e.mux.Lock()
+	defer e.mux.Unlock()
+
+	delete(e.ack, id)
+}