[DirectX] Root signature's `DescriptorTableView` has undefined behaviour for version 1.0 root signatures.

[bogner]

We currently have the "DescriptorTableView" load a DirectX::DescriptorTable with a type like so:

struct DescriptorTable {
  uint32_t NumRanges;
  uint32_t RangesOffset;
  ViewArray<dxbc::RTS0::v2::DescriptorRange> Ranges;
};

However, we set up the ranges view like so:

    size_t RangeSize = sizeof(dxbc::RTS0::v1::DescriptorRange);
    if (Version > 1)
      RangeSize = sizeof(dxbc::RTS0::v2::DescriptorRange);

    Table.Ranges.Stride = RangeSize;
    Table.Ranges.Data =
        ParamData.substr(2 * sizeof(uint32_t), Table.NumRanges * RangeSize);

This invokes undefined behaviour. It is not legal to store a dxbc::RTS0::v1::DescriptorRange in an object of type dxbc::RTS0::v2::DescriptorRange (the inheritance is in the other direction. Furthermore, dxbc::RTS0::v2::DescriptorRange will not fit in sizeof(dxbc::RTS0::v1::DescriptorRange), and the last field (currently Flags) will overlap with the next object.

Note: this may become moot depending on the fix to #145438, as that issue implies that we won't be able to have an inheritance relationship between the versions of DescriptorRange at all.