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/telegram/updates/update.go

@@ -0,0 +1,53 @@
+package updates
+
+import (
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+type update struct {
+	Value    any
+	State    int
+	Count    int
+	Entities entities
+}
+
+func (u update) start() int { return u.State - u.Count }
+
+func (u update) end() int { return u.State }
+
+// Entities contains update entities.
+type entities struct {
+	Users []tg.UserClass
+	Chats []tg.ChatClass
+}
+
+// Merge merges entities.
+func (e *entities) Merge(from entities) {
+	for _, candidate := range from.Users {
+		merge := true
+		for _, exist := range e.Users {
+			if exist.GetID() == candidate.GetID() {
+				merge = false
+				break
+			}
+		}
+
+		if merge {
+			e.Users = append(e.Users, candidate)
+		}
+	}
+
+	for _, candidate := range from.Chats {
+		merge := true
+		for _, exist := range e.Chats {
+			if exist.GetID() == candidate.GetID() {
+				merge = false
+				break
+			}
+		}
+
+		if merge {
+			e.Chats = append(e.Chats, candidate)
+		}
+	}
+}