add C-y to yank picker selection to clipboard

[kirawi]

I think this is useful for easily searching diagnostics online.

[crushingCodes]

i was just looking for this as i usually copy error messages often and its already a pr nice!

[CBenoit]

Hi @kirawi Any chance you could complete this PR?

[Antonio-Bennett]

@kirawi Could this be pushed ahead again? This is a super helpful PR! Just switched over from neovim and this is definitely something I miss :)

[kirawi]

I will finish this PR tomorrow or the day after.