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/_schema/legacy.tl

@@ -0,0 +1,36 @@
+int#a8509bda ? = Int;
+
+long#22076cba ? = Long;
+
+double#2210c154 ? = Double;
+
+string#b5286e24 ? = String;
+
+bytes#e937bb82 = Bytes;
+
+true#3fedd339 = True;
+
+boolFalse#bc799737 = Bool;
+
+boolTrue#997275b5 = Bool;
+
+error#c4b9f9bb code:int text:string = Error;
+
+ipPort#d433ad73 ipv4:int port:int = IpPort;
+
+ipPortSecret#37982646 ipv4:int port:int secret:bytes = IpPort;
+
+accessPointRule#4679b65f phone_prefix_rules:string dc_id:int ips:vector<IpPort> = AccessPointRule;
+
+help.configSimple#5a592a6c date:int expires:int rules:vector<AccessPointRule> = help.ConfigSimple;
+
+inputPeerPhotoFileLocationLegacy#27d69997 flags:# big:flags.0?true peer:InputPeer volume_id:long local_id:int = InputFileLocation;
+
+inputStickerSetThumbLegacy#dbaeae9 stickerset:InputStickerSet volume_id:long local_id:int = InputFileLocation;
+
+
+---functions---
+
+test.useError#ee75af01 = Error;
+
+test.useConfigSimple#f9b7b23d = help.ConfigSimple;