Make `EditorVCSInterface` proxy functions virtual in C++
Make `EditorVCSInterface` proxy functions virtual in C++

Allows to implement VCS plugins via C++ modules without affecting
the existing script instance mechanism.

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