Improve shortcut keys assignation from context menu

I propose a new function: possibility to chose the same shortcut with a warning: one other stuff or several has already the same shortcut. do you want to confirm? if yes they will appear in a common menu. so now we can really personalize blender...but this is a new different idea in fact i do a subject

yes I added a subject on how to get back alt c or ctrl c in 2.8 keys because having a shortcut for each one is less good that menu from 2.79 with several functions and 1shortcut.

Great idea.