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>

vendor/github.com/Benau/go_rlottie/go_rlottie.go

@@ -0,0 +1,56 @@
+package go_rlottie
+
+/*
+#cgo !windows LDFLAGS: -lm
+#cgo windows CFLAGS: -DRLOTTIE_BUILD=0
+#cgo windows CXXFLAGS: -DRLOTTIE_BUILD=0
+#cgo CXXFLAGS: -std=c++14 -fno-exceptions -fno-asynchronous-unwind-tables -fno-rtti -Wall -fvisibility=hidden -Wnon-virtual-dtor -Woverloaded-virtual -Wno-unused-parameter
+#include "rlottie_capi.h"
+void lottie_configure_model_cache_size(size_t cacheSize);
+*/
+import "C"
+import "unsafe"
+
+type Lottie_Animation *C.Lottie_Animation
+
+func LottieConfigureModelCacheSize(size uint) {
+	C.lottie_configure_model_cache_size(C.size_t(size))
+}
+
+func LottieAnimationFromData(data string, key string, resource_path string) Lottie_Animation {
+	var animation Lottie_Animation
+	animation = C.lottie_animation_from_data(C.CString(data), C.CString(key), C.CString(resource_path))
+	return animation
+}
+
+func LottieAnimationDestroy(animation Lottie_Animation) {
+	C.lottie_animation_destroy(animation)
+}
+
+func LottieAnimationGetSize(animation Lottie_Animation) (uint, uint) {
+	var width C.size_t
+	var height C.size_t
+	C.lottie_animation_get_size(animation, &width, &height)
+	return uint(width), uint(height)
+}
+
+func LottieAnimationGetTotalframe(animation Lottie_Animation) uint {
+	return uint(C.lottie_animation_get_totalframe(animation))
+}
+
+func LottieAnimationGetFramerate(animation Lottie_Animation) float64 {
+	return float64(C.lottie_animation_get_framerate(animation))
+}
+
+func LottieAnimationGetFrameAtPos(animation Lottie_Animation, pos float32) uint {
+	return uint(C.lottie_animation_get_frame_at_pos(animation, C.float(pos)))
+}
+
+func LottieAnimationGetDuration(animation Lottie_Animation) float64 {
+	return float64(C.lottie_animation_get_duration(animation))
+}
+
+func LottieAnimationRender(animation Lottie_Animation, frame_num uint, buffer []byte, width uint, height uint, bytes_per_line uint) {
+	var ptr *C.uint32_t = (*C.uint32_t)(unsafe.Pointer(&buffer[0]));
+	C.lottie_animation_render(animation, C.size_t(frame_num), ptr, C.size_t(width), C.size_t(height), C.size_t(bytes_per_line))
+}