DDS: Fix loading files without DDSD_CAPS or DDSD_PIXELFORMAT
DDS: Fix loading files without DDSD_CAPS or DDSD_PIXELFORMAT

MSDN says:

> When you write .dds files, you should set the DDSD_CAPS and
> DDSD_PIXELFORMAT flags, and for mipmapped textures you should also
> set the DDSD_MIPMAPCOUNT flag. However, when you read a .dds file,
> you should not rely on the DDSD_CAPS, DDSD_PIXELFORMAT, and
> DDSD_MIPMAPCOUNT flags being set because some writers of such a file
> might not set these flags.

https://docs.microsoft.com/en-us/windows/win32/direct3ddds/dds-header

¯\_(ツ)_/¯

Fixes #39516.

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