require List::Util 1.50 and delegate for head and tail

[Grinnz]

Summary

Delegate to the head and tail functions from List::Util 1.50.

Note that this raises the minimum Perl version that fatpacked Mojolicious will work on from 5.22 to 5.28, as List::Util cannot be fatpacked.

Motivation

Code cleanliness and efficiency.

References

#1360

[Grinnz]

An alternative is to delegate only if List::Util 1.50 is available, which retains the performance benefit if any on newer perls, but adds more code.

[Grinnz]

I am closing this as I cannot find a set of data where delegating to List::Util outperforms the resulting sub call overhead.