Add waitany and waitall functions to wait multiple tasks at once

[mrkn]

I would like to propose adding two functions, waitany and waitall, discussed in the issue #53226. These functions wait for multiple tasks at once. The waitany function blocks until one task finishes. The waitall function blocks until all tasks finish. There is an optional keyword argument, failfast, for the waitall function. The default of failfast is false. The waitall function will immediately stop if any task ends with an exception when the failfast is true.

This is my own implementation, but I have regrets about the type of the first argument. I wanted to represent a container type from which Task objects can be taken out using the iterate function, but it seems impossible in current Julia, so I used a union type of AbstractVector, Tuple, and Set. I would like to know if there is a better way to write this part.

[vtjnash]

This seems quite great. It has got lots of annoying details if anyone was trying to emulate it themself, but seems fairly straightforward internally once you work out those details. I think we are ready to merge it, unless there is anything else of concern with it from anyone? One observation I might suggest is that we add another flag throw (related to failfast) that defines whether it should fail with CompositeException when exception is set (independent of failfast)?

This may also be a good drop-in replacement for the Experiment.sync_end implementation, with waitall and failfast, which may be a good demo of it in use?

[quinnj]

Thanks for all the persistence and effort here @mrkn! Really great to get this in!

[IanButterworth]

Adding backport to 1.11 because we want this in 1.11 for #54674

[IanButterworth]

#54760 means we no longer need waitany on 1.11 so I'm removing the backport label