`maybe_step_through_wrapper!` steps through function-like objects

[pfitzseb]

See https://discourse.julialang.org/t/debugging-function-like-object-under-juno/26079.

Smaller repro is

struct FunLike
   value::Int
end

function (f::FunLike)(x)
   y = sin(3)
   f.value
end

f = FunLike(3)

f(3)

where

julia> @code_typed f(3)
CodeInfo(
1 ─ %1 = Base.getfield(f, :value)::Int64
└──      return %1
) => Int64

That means that the isexpr(last, :call) && any(isequal(SlotNumber(1)), last.args) check returns true.
I'm not sure how to best handle this -- special casing getfield/setfield!/getproperty/setproperty! doesn't seem completely stupid, but might not be enough. I suppose we could also check if the method we're in belongs to a Function (as opposed to some other type), but then we'd probably lose the ability to step through f(x=3). Any ideas?