Improve hackability for VM lists

Would be nice to have `!vm.list` support index elements enough to allow for type conversion (so you could author `!vm.list` and have it switch to i32 or i64 based on target VM configuration). If there was a standard list we could avoid this; or we could have an intermediate `!iree.list` that let the lowering take care of things (would also avoid the need to leak `vm` as high up in the stack).

Would also be nice to have a `vm.list.reset` that took a variadic list of args and did the resize + sets. This would shrink the IR a lot (and be better at runtime too).

Motivating example, to build a shape:

```mlir
%rank = constant 4 : i32
vm.list.resize %shape, %rank : (!vm.list, i32)
%i0 = constant 0 : i32
%i1 = constant 1 : i32
%i2 = constant 2 : i32
%i3 = constant 3 : i32
%c1 = constant 1 : i32
%c3 = constant 3 : i32
%c8 = constant 8 : i32
vm.list.set.i32 %shape, %i0, %c1 : (!vm.list, i32, i32)
vm.list.set.i32 %shape, %i1, %c8 : (!vm.list, i32, i32)
vm.list.set.i32 %shape, %i2, %c8 : (!vm.list, i32, i32)
vm.list.set.i32 %shape, %i3, %c3 : (!vm.list, i32, i32)
```

Start by tracing the existing vm.list.resize and vm.list.set.i32 operations shown in the MLIR example. Clarify whether indexed type conversion, an intermediate !iree.list, or vm.list.reset is in scope; done requires an agreed design and defined behavior for the motivating shape-building case.

Written by the indexing model from the issue text.