[Clock] A new component to decouple applications from the system clock

[fabpot]

Q	A
Feature PR	symfony/symfony#46715
PR author(s)	@nicolas-grekas
Merged in	6.2

[wouterj]

This deserves a new article in components/. As the component is quite minimal, this will be a nice short article :)

Anyone up to writing the docs for this? (@nicolas-grekas?)

[dbrumann]

I can do this one together with #17434