Convert .tgs with go libraries (and cgo) (telegram) (#1569)

This commit adds support for go/cgo tgs conversion when building with the -tags `cgo`
The default binaries are still "pure" go and uses the old way of converting.

* Move lottie_convert.py conversion code to its own file

* Add optional libtgsconverter

* Update vendor

* Apply suggestions from code review

* Update bridge/helper/libtgsconverter.go

Co-authored-by: Wim <wim@42.be>

bridge/helper/libtgsconverter.go

@@ -0,0 +1,34 @@
+// +build cgo
+
+package helper
+
+import (
+	"fmt"
+	"github.com/Benau/tgsconverter/libtgsconverter"
+	"github.com/sirupsen/logrus"
+)
+
+func CanConvertTgsToX() error {
+	return nil
+}
+
+// ConvertTgsToX convert input data (which should be tgs format) to any format supported by libtgsconverter
+func ConvertTgsToX(data *[]byte, outputFormat string, logger *logrus.Entry) error {
+	options := libtgsconverter.NewConverterOptions()
+	options.SetExtension(outputFormat)
+	blob, err := libtgsconverter.ImportFromData(*data, options)
+	if err != nil {
+		return fmt.Errorf("failed to run libtgsconverter.ImportFromData: %s", err.Error())
+	}
+
+	*data = blob
+	return nil
+}
+
+func SupportsFormat(format string) bool {
+	return libtgsconverter.SupportsExtension(format)
+}
+
+func LottieBackend() string {
+	return "libtgsconverter"
+}