2.0: Reconsider Pairs iteration/getindex API?

[jariji]

In 1.9,

julia> first(pairs([10,20,30]))
1 => 10

julia> pairs([10,20,30])[1]
10

apparently because first makes an iterator of pairs and getindex makes a dictlike of pairs. I find this complicated. Maybe there is another design possible, perhaps inspired by Dictionaries.jl.

[mbauman]

I think this is a specific case of the more wholistic #24019.