Add descriptive tooltips in VS editor
Add descriptive tooltips in VS editor

In the Visual Script editor, the override icon is not very clear what it's intended purpose is for. Currently, its tooltip just says: "Function:" which is the same tooltip as the "add new function" icon.

To resolve this issue, this PR adds descriptive tooltips to the following icons in the Visual Script editor: 
-Override Function
-Add Function
-Add Variable
-Add Signal
Valentactive/godot,DmitriySalnikov/godot,josempans/godot,DmitriySalnikov/godot,MarianoGnu/godot,BastiaanOlij/godot,Paulloz/godot,sanikoyes/godot,vnen/godot,akien-mga/godot,Faless/godot,Shockblast/godot,Zylann/godot,pkowal1982/godot,Shockblast/godot,ex/godot,ZuBsPaCe/godot,MarianoGnu/godot,sanikoyes/godot,vkbsb/godot,ZuBsPaCe/godot,Faless/godot,ex/godot,vnen/godot,godotengine/godot,ZuBsPaCe/godot,Valentactive/godot,akien-mga/godot,guilhermefelipecgs/godot,ZuBsPaCe/godot,ZuBsPaCe/godot,guilhermefelipecgs/godot,ex/godot,josempans/godot,ex/godot,Paulloz/godot,vkbsb/godot,Zylann/godot,godotengine/godot,guilhermefelipecgs/godot,honix/godot,sanikoyes/godot,Zylann/godot,pkowal1982/godot,ZuBsPaCe/godot,guilhermefelipecgs/godot,DmitriySalnikov/godot,Shockblast/godot,ex/godot,Valentactive/godot,DmitriySalnikov/godot,pkowal1982/godot,BastiaanOlij/godot,guilhermefelipecgs/godot,Valentactive/godot,pkowal1982/godot,BastiaanOlij/godot,vnen/godot,Faless/godot,honix/godot,DmitriySalnikov/godot,godotengine/godot,pkowal1982/godot,honix/godot,josempans/godot,Zylann/godot,vkbsb/godot,ex/godot,josempans/godot,Shockblast/godot,guilhermefelipecgs/godot,akien-mga/godot,DmitriySalnikov/godot,Shockblast/godot,vnen/godot,MarianoGnu/godot,MarianoGnu/godot,akien-mga/godot,Valentactive/godot,sanikoyes/godot,sanikoyes/godot,MarianoGnu/godot,firefly2442/godot,firefly2442/godot,Shockblast/godot,vnen/godot,josempans/godot,josempans/godot,BastiaanOlij/godot,Faless/godot,Valentactive/godot,DmitriySalnikov/godot,BastiaanOlij/godot,godotengine/godot,guilhermefelipecgs/godot,MarianoGnu/godot,Paulloz/godot,pkowal1982/godot,guilhermefelipecgs/godot,sanikoyes/godot,firefly2442/godot,MarianoGnu/godot,josempans/godot,MarianoGnu/godot,Faless/godot,vkbsb/godot,Zylann/godot,BastiaanOlij/godot,godotengine/godot,Faless/godot,vnen/godot,akien-mga/godot,godotengine/godot,Zylann/godot,firefly2442/godot,vkbsb/godot,BastiaanOlij/godot,vkbsb/godot,Paulloz/godot,honix/godot,honix/godot,sanikoyes/godot,vkbsb/godot,vkbsb/godot,Valentactive/godot,godotengine/godot,firefly2442/godot,honix/godot,ex/godot,vnen/godot,Faless/godot,Valentactive/godot,Shockblast/godot,akien-mga/godot,firefly2442/godot,BastiaanOlij/godot,Paulloz/godot,akien-mga/godot,pkowal1982/godot,Faless/godot,ZuBsPaCe/godot,firefly2442/godot,akien-mga/godot,vnen/godot,Shockblast/godot,Paulloz/godot,josempans/godot,Zylann/godot,ex/godot,sanikoyes/godot,godotengine/godot,Paulloz/godot,pkowal1982/godot,Zylann/godot,firefly2442/godot,ZuBsPaCe/godot