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/internal/version/version.go

@@ -0,0 +1,36 @@
+// Package version contains gotd module version getter.
+package version
+
+import (
+	"runtime/debug"
+	"strings"
+	"sync"
+)
+
+var versionOnce struct {
+	version string
+	sync.Once
+}
+
+// GetVersion optimistically gets current client version.
+//
+// Does not handle replace directives.
+func GetVersion() string {
+	versionOnce.Do(func() {
+		info, ok := debug.ReadBuildInfo()
+		if !ok {
+			return
+		}
+		// Hard-coded package name. Probably we can generate this via parsing
+		// the go.mod file.
+		const pkg = "go.mau.fi/mautrix-telegram/pkg/gotd"
+		for _, d := range info.Deps {
+			if strings.HasPrefix(d.Path, pkg) {
+				versionOnce.version = d.Version
+				break
+			}
+		}
+	})
+
+	return versionOnce.version
+}