Set types of boxed variables in abstract_eval_nonlinearized_foreigncall_name

[JamesWrigley]

This prevents invalidations of isready() from loading Distributed on 1.12:

 inserting isready(pool::Distributed.WorkerPool) @ Distributed ~/.julia/juliaup/julia-1.12.1+0.x64.linux.gnu/share/julia/stdlib/v1.12/Distributed/src/workerpool.jl:168 invalidated:
   mt_backedges: 1: signature Tuple{typeof(isready), Any} triggered MethodInstance for (::Compiler.var"#evalargs#abstract_eval_nonlinearized_foreigncall_name##0"{Expr, Compiler.StatementState, Compiler.Future{Compiler.CallMeta}, Vector{Any}, Int64})(::Compiler.AbstractInterpreter, ::Compiler.InferenceState) (0 children)
                 2: signature Tuple{typeof(isready), Any} triggered MethodInstance for (::Compiler.var"#evalargs#abstract_eval_nonlinearized_foreigncall_name##0"{Expr, Compiler.StatementState, Compiler.Future{Compiler.CallMeta}, Vector{Any}, Int64})(::Compiler.NativeInterpreter, ::Compiler.InferenceState) (0 children)
                 3: signature Tuple{typeof(isready), Any} triggered MethodInstance for (::Compiler.var"#evalargs#abstract_eval_nonlinearized_foreigncall_name##0"{Expr, Compiler.StatementState, Compiler.Future{Compiler.CallMeta}, Vector{Any}, Int64})(::Compiler.AbstractInterpreter, ::Compiler.InferenceState) (249 children)

I think ideally it wouldn't use a closure at all, but I'm not familiar enough with the code to refactor it that much. I'm making the PR against the release-1.12 branch because this function is deleted entirely on master by #59165.

[JamesWrigley]

This is well beyond my comfort zone so I can't say for sure, but I think the build/test failures are unrelated. I had a look at the return types of functions that assign to ai and res and they all seem to be Future.