Cleanup of Visual Studio project generation (#12929)
Cleanup of Visual Studio project generation (#12929)

Visual studio project file creation had some problems. Files with c extension were listed with cpp extension. Some include files that did not exist were added to the project.
This change ensures a file exists before adding it to the project.
vnen/godot,Paulloz/godot,akien-mga/godot,okamstudio/godot,ZuBsPaCe/godot,pkowal1982/godot,akien-mga/godot,mcanders/godot,vkbsb/godot,n-pigeon/godot,n-pigeon/godot,okamstudio/godot,vnen/godot,vnen/godot,NateWardawg/godot,godotengine/godot,NateWardawg/godot,ex/godot,mcanders/godot,godotengine/godot,Shockblast/godot,NateWardawg/godot,firefly2442/godot,sanikoyes/godot,firefly2442/godot,DmitriySalnikov/godot,n-pigeon/godot,groud/godot,Valentactive/godot,Valentactive/godot,vnen/godot,josempans/godot,guilhermefelipecgs/godot,josempans/godot,akien-mga/godot,Zylann/godot,BastiaanOlij/godot,vkbsb/godot,Zylann/godot,NateWardawg/godot,BastiaanOlij/godot,DmitriySalnikov/godot,josempans/godot,ex/godot,firefly2442/godot,groud/godot,guilhermefelipecgs/godot,NateWardawg/godot,vkbsb/godot,godotengine/godot,honix/godot,RandomShaper/godot,Zylann/godot,MarianoGnu/godot,okamstudio/godot,DmitriySalnikov/godot,Valentactive/godot,BastiaanOlij/godot,Shockblast/godot,RandomShaper/godot,Valentactive/godot,Shockblast/godot,godotengine/godot,pkowal1982/godot,BastiaanOlij/godot,Faless/godot,pkowal1982/godot,Shockblast/godot,akien-mga/godot,RandomShaper/godot,NateWardawg/godot,Faless/godot,godotengine/godot,honix/godot,josempans/godot,Faless/godot,vkbsb/godot,josempans/godot,mcanders/godot,sanikoyes/godot,honix/godot,Shockblast/godot,honix/godot,akien-mga/godot,ZuBsPaCe/godot,RandomShaper/godot,groud/godot,ZuBsPaCe/godot,firefly2442/godot,vkbsb/godot,MarianoGnu/godot,guilhermefelipecgs/godot,mcanders/godot,godotengine/godot,MarianoGnu/godot,mcanders/godot,sanikoyes/godot,sanikoyes/godot,Paulloz/godot,n-pigeon/godot,n-pigeon/godot,honix/godot,sanikoyes/godot,Zylann/godot,josempans/godot,MarianoGnu/godot,BastiaanOlij/godot,ZuBsPaCe/godot,ex/godot,guilhermefelipecgs/godot,sanikoyes/godot,Valentactive/godot,ex/godot,Faless/godot,ZuBsPaCe/godot,ZuBsPaCe/godot,vkbsb/godot,sanikoyes/godot,DmitriySalnikov/godot,firefly2442/godot,NateWardawg/godot,okamstudio/godot,Shockblast/godot,RandomShaper/godot,Faless/godot,ex/godot,BastiaanOlij/godot,Valentactive/godot,ZuBsPaCe/godot,okamstudio/godot,pkowal1982/godot,Zylann/godot,honix/godot,pkowal1982/godot,DmitriySalnikov/godot,Paulloz/godot,groud/godot,ex/godot,Valentactive/godot,ex/godot,akien-mga/godot,Paulloz/godot,Shockblast/godot,okamstudio/godot,Paulloz/godot,Faless/godot,Zylann/godot,n-pigeon/godot,Zylann/godot,MarianoGnu/godot,n-pigeon/godot,okamstudio/godot,firefly2442/godot,vkbsb/godot,okamstudio/godot,vnen/godot,guilhermefelipecgs/godot,guilhermefelipecgs/godot,groud/godot,Paulloz/godot,ex/godot,MarianoGnu/godot,pkowal1982/godot,Valentactive/godot,godotengine/godot,mcanders/godot,josempans/godot,Faless/godot,MarianoGnu/godot,RandomShaper/godot,godotengine/godot,vkbsb/godot,akien-mga/godot,Shockblast/godot,MarianoGnu/godot,josempans/godot,groud/godot,vnen/godot,guilhermefelipecgs/godot,Faless/godot,okamstudio/godot,okamstudio/godot,sanikoyes/godot,pkowal1982/godot,RandomShaper/godot,akien-mga/godot,Zylann/godot,BastiaanOlij/godot,NateWardawg/godot,vnen/godot,Paulloz/godot,firefly2442/godot,guilhermefelipecgs/godot,vnen/godot,DmitriySalnikov/godot,pkowal1982/godot,BastiaanOlij/godot,DmitriySalnikov/godot,ZuBsPaCe/godot,firefly2442/godot,NateWardawg/godot