gltf: Fix validation errors due to chunk padding and empty skins.
gltf: Fix validation errors due to chunk padding and empty skins.

GLB chunk padding length calculation was backwards and missing for the BIN chunk.
Fixed error caused by "skins":[] when no skins were present.
Finally, encode animations before textures to avoid accessor misalignment due to texture byteLength.

Valentactive/godot,vnen/godot,Zylann/godot,Zylann/godot,vkbsb/godot,ZuBsPaCe/godot,BastiaanOlij/godot,akien-mga/godot,Shockblast/godot,ZuBsPaCe/godot,Faless/godot,Zylann/godot,firefly2442/godot,guilhermefelipecgs/godot,ZuBsPaCe/godot,Zylann/godot,Faless/godot,akien-mga/godot,BastiaanOlij/godot,BastiaanOlij/godot,firefly2442/godot,vkbsb/godot,vkbsb/godot,vnen/godot,Shockblast/godot,guilhermefelipecgs/godot,vnen/godot,firefly2442/godot,Shockblast/godot,Faless/godot,ZuBsPaCe/godot,firefly2442/godot,sanikoyes/godot,godotengine/godot,guilhermefelipecgs/godot,Shockblast/godot,sanikoyes/godot,godotengine/godot,BastiaanOlij/godot,pkowal1982/godot,godotengine/godot,josempans/godot,Zylann/godot,Faless/godot,ZuBsPaCe/godot,pkowal1982/godot,firefly2442/godot,guilhermefelipecgs/godot,godotengine/godot,vkbsb/godot,vnen/godot,sanikoyes/godot,Shockblast/godot,godotengine/godot,vnen/godot,godotengine/godot,guilhermefelipecgs/godot,Faless/godot,akien-mga/godot,vnen/godot,Faless/godot,pkowal1982/godot,Valentactive/godot,firefly2442/godot,akien-mga/godot,Valentactive/godot,guilhermefelipecgs/godot,pkowal1982/godot,Shockblast/godot,vkbsb/godot,josempans/godot,godotengine/godot,Zylann/godot,ZuBsPaCe/godot,BastiaanOlij/godot,guilhermefelipecgs/godot,josempans/godot,josempans/godot,ZuBsPaCe/godot,firefly2442/godot,josempans/godot,BastiaanOlij/godot,akien-mga/godot,sanikoyes/godot,pkowal1982/godot,akien-mga/godot,vkbsb/godot,Valentactive/godot,Faless/godot,Faless/godot,Shockblast/godot,pkowal1982/godot,vnen/godot,Valentactive/godot,BastiaanOlij/godot,Shockblast/godot,josempans/godot,sanikoyes/godot,vnen/godot,Zylann/godot,vkbsb/godot,pkowal1982/godot,josempans/godot,BastiaanOlij/godot,Valentactive/godot,pkowal1982/godot,firefly2442/godot,godotengine/godot,sanikoyes/godot,Valentactive/godot,Zylann/godot,vkbsb/godot,akien-mga/godot,josempans/godot,Valentactive/godot,ZuBsPaCe/godot,sanikoyes/godot,guilhermefelipecgs/godot,sanikoyes/godot,akien-mga/godot