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/message/entity/options.go

@@ -0,0 +1,20 @@
+package entity
+
+import "go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+
+// Formatter is a message entity constructor.
+type Formatter func(offset, limit int) tg.MessageEntityClass
+
+// Plain formats message as plain text.
+func (b *Builder) Plain(s string) *Builder {
+	_, _ = b.WriteString(s)
+	b.lastFormatIndex = len(b.entities)
+	return b
+}
+
+// Format formats message using given formatters.
+func (b *Builder) Format(s string, formats ...Formatter) *Builder {
+	return b.appendMessage(s, formats...)
+}
+
+//go:generate go run go.mau.fi/mautrix-telegram/pkg/gotd/telegram/message/internal/mkentity -output options.gen.go