[LLDB] Add formatters for MSVC STL std::deque (#150097)
This PR adds synthetic children for std::deque from MSVC's STL.
Similar to libstdc++ and libc++, the elements are in a `T**`, so we need
to "subscript" twice. The [NatVis for
deque](https://github.com/microsoft/STL/blob/313964b78a8fd5a52e7965e13781f735bcce13c5/stl/debugger/STL.natvis#L1103-L1112)
uses `_EEN_DS` which contains the block size. We can't access this, but
we can access the [constexpr
`_Block_size`](https://github.com/microsoft/STL/blob/313964b78a8fd5a52e7965e13781f735bcce13c5/stl/inc/deque#L641).
Towards #24834.
