In debugging, arguments are always shown instead of locals

Given this:
```
let inp = seq { 1 .. 3 }
let h3 x =
for x in inp do
printfn $"hello, x = {x}"
printfn "hello"

h3 10
```
then when you stop inside the loop, the value `x` shows as `10` even though in the loop it is `1`, `2`, `3`. The locals simply aren't shown at all.

I'm not actually sure there is a fix to this without #2544 knowing how to resolve the names according to F# rules. It looks to me like the C# locals display is simply deciding not to show any locals that conflict with an argument name (which they never do according to C# rules)

Note this may have changed in recent VS, I've not seen the problem before, though it's likely it's just always been there.