I have heard that an option for this already exists in an early state.If you go to about:config and set the property cookiebanners.service.mode to 2, they should auto-refuse cookies and stop bothering you.A little more info about these new options he...
I used to use this feature too.For a workaround, while you're waiting for possible implementation in Firefox, I found I get pretty good results from saving my favorite dictionary site as a search engine on Firefox, and setting its shortcut to @def or...