RFC: patched searchsortedfirst, searchsortedlast, searchsorted, and insorted available in DataStructures.jl?

A number of Julia users including me have been stung by unexpected behavior in the searchsorted suite of functions in Base, namely, that the by transformation is applied also to the key. There is a recent discussion (https://discourse.julialang.org/t/problem-with-searchsortedfirst/73332/31) of this on discourse, but it has come up before. This makes the suite awkward to use when the by function is something like first that extracts part of a larger object. A PR https://github.com/JuliaLang/julia/pull/35418 to fix this problem was rejected by the core team. I am wondering: Would it make sense to offer patched versions of these Base function in the DataStructures package? Note DataStructures already overloads Base.searchsortedfirst, etc., specifically for sorted containers, so it would not be totally random.

Start by reviewing DataStructures.jl's existing overloads for Base.searchsortedfirst, searchsortedlast, searchsorted, and insorted. Then read the linked Discourse discussion and rejected Julia PR #35418 to understand the proposed behavior. Done means reaching a maintainer decision on whether patched versions belong in DataStructures and defining their intended scope.