Implement keyboard shortcut to pin selection to Github Copilot Chat as context

At present if I am looking at the context of a file and highlight/select some portion thereof, I see that that selection is provisionally added to the Github Copilot Chat, but if I then change what I have selected, what is added to the chat as context updates unless I click the `Pin selection` GUI element (circled in red)

- I think this functionality should be key bindable and have a default key bind (say, ctrl+alt+i, or maybe ctrl+shift+i, whatever). This would make it much easier to quickly select relevant section to add context, without having to rely on a tiny little button. I could then use my keyboard to quickly move through my files, adding relevant selections to the chat's context, then when I'm done I can go to the chat itself to add instructions.