SE-0202 amendment: Remove `Collection.randomElement` requirement.
SE-0202 amendment: Remove `Collection.randomElement` requirement.

As a protocol requirement, this poses a potential forward compatibility hazard with move-only collections, and it's far from the only collection operation that would trap on a huge range used as a collection.

rballard/swift-evolution,allevato/swift-evolution,DevAndArtist/swift-evolution,hartbit/swift-evolution,abertelrud/swift-evolution,DevAndArtist/swift-evolution,abertelrud/swift-evolution,hartbit/swift-evolution,natecook1000/swift-evolution,allevato/swift-evolution,Nirma/swift-evolution,jckarter/swift-evolution,apple/swift-evolution,Nirma/swift-evolution,ddunbar/swift-evolution,jckarter/swift-evolution,anandabits/swift-evolution,anandabits/swift-evolution,airspeedswift/swift-evolution,apple/swift-evolution,ddunbar/swift-evolution,natecook1000/swift-evolution,rballard/swift-evolution,airspeedswift/swift-evolution