[GlobalOpt] Fix crash in RaiseSpecialOps on buffer-semantics named ops (#24626)

## Problem

Passing a `linalg.matmul` (or any named contraction/convolution op) with
**memref / buffer operands** to `iree-compile` crashes with a hard
assert instead of a clean diagnostic:

```
Assertion failed: (index < size() && "invalid index into type range"),
function operator[], file TypeRange.h, line 156.
...
NamedImplicitCastOpConversion<linalg::ContractionOpInterface>::matchAndRewrite(...)
```

`NamedImplicitCastOpConversion::matchAndRewrite` in
`GlobalOptimization/RaiseSpecialOps.cpp` reasons about the op's results
(`getResultTypes()[0]`) and rewrites its body region, both of which
assume tensor semantics. A buffer-semantics linalg op writes to an
output buffer and has **zero results**, so `getResultTypes()[0]` indexes
an empty `TypeRange` and aborts.

## Fix

Bail out via `hasPureTensorSemantics()` before touching results,
matching the guards already used elsewhere in this file (e.g. lines 48,
231). The op is left untouched and compilation proceeds normally.

## Verification (local, llvm-cpu)

A/B on identical current `main` sources, exact reproducer from the
issue:

| Build | `iree-compile ... memref matmul` |
|---|---|
| unfixed (`main`) | exit **134**, assert in
`NamedImplicitCastOpConversion` |
| fixed (this PR) | exit **0**, compiles cleanly to a valid `.vmfb` |

- Added lit test `@matmul_memref_no_crash` in `raise_special_ops.mlir`.
- Full `raise_special_ops.mlir` lit suite passes.

Fixes #24624

Signed-off-by: Alex-Wengg <hanweng9@gmail.com>