[BUG]: tuple_size_structured_bindings test fails on MSVC — late tuple_size specialization not picked up by structured binding

### Type of Bug
Runtime Error

### Component
libcu++

### Describe the bug

`std/utilities/tuple/tuple.tuple/tuple.helper/tuple_size_structured_bindings.pass.cpp` fails at line 153 on MSVC:

```
Assertion failed: p == -1, ... tuple_size_structured_bindings.pass.cpp, line 153
```

`test_after_tuple_size_specialization` declares `Test const t{99}`, then `auto& [p] = t` after a `std::tuple_size` specialization and matching `get<0>` returning `-1`. clang/gcc route the binding through the tuple protocol (`p == -1`); MSVC keeps binding to the underlying member (`p == 99`).

The test already guards an analogous NVRTC quirk:

```cpp
#if !_CCCL_COMPILER(NVRTC) // nvbug4053842
assert(p == -1);
#endif
```

MSVC needs an equivalent guard, or the structured-binding lookup needs to honor late `tuple_size` specializations under MSVC.

Reproduces on every MSVC libcu++ Test job: CTK12.9/MSVC14.44 and CTK13.2/MSVC14.50, C++20, RTX4090 and H100. Discovered while enabling libcu++ MSVC GPU jobs in #5725, which marks the test `// UNSUPPORTED: msvc` to unblock; this issue tracks the underlying behavior.

### How to Reproduce

1. Check out PR #5725.
2. Build and run `libcudacxx.test.lit` against MSVC (CTK12.9/MSVC14.44 or CTK13.2/MSVC14.50, C++20).

### Expected behavior

After specializing `std::tuple_size` with `value = 1` and a matching `get<0>` returning `-1`, `auto& [p] = t` should bind `p` to `-1`, matching clang/gcc.

### Operating System

Windows Server (CI runner image)

### NVCC version

CTK 12.9 (MSVC 14.44.35207) and CTK 13.2 (MSVC 14.50.35717).