[Console] Add signal event

[fabpot]

Q	A
Feature PR	symfony/symfony#33729
PR author(s)	@marie
Merged in	5.2-dev

[javiereguiluz]

When documenting, keep in mind these changes that were merged later: symfony/symfony#37827

[lyrixx]

And symfony/symfony#38845

[javiereguiluz]

Fixed by #15717 and #15741.