Re-implement Member#add_role
Re-implement Member#add_role

VxJasonxV/discordrb,megumisonoda/discordrb,Roughsketch/discordrb,VxJasonxV/discordrb,Roughsketch/discordrb,megumisonoda/discordrb,meew0/discordrb,meew0/discordrb