Node: make _generate_serial_child_name manipulate numbers as String
Node: make _generate_serial_child_name manipulate numbers as String

The conversion from an String to int can overflow int and int64
so it is safer to manipulate strings when we try to find the next
available name for a Node.

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