[mlir][ptr] Add translations to LLVMIR for ptr ops. (#156355)

Implements translation from ptr dialect to LLVM IR for core pointer
operations:
- `ptr.ptr_add` -> `getelementptr`
- `ptr.load` -> `load` with atomic ordering, volatility, and metadata
support
- `ptr.store` -> `store` with atomic ordering, volatility, and metadata
support
- `ptr.type_offset` -> GEP-based size computation

Example:

```mlir
llvm.func @test(%arg0: !ptr.ptr<#llvm.address_space<0>>) {
  %0 = ptr.type_offset f64 : i32
  %1 = ptr.ptr_add inbounds %arg0, %0 : !ptr.ptr<#llvm.address_space<0>>, i32
  %2 = ptr.load volatile %1 : !ptr.ptr<#llvm.address_space<0>> -> f64
  ptr.store %2, %arg0 : f64, !ptr.ptr<#llvm.address_space<0>>
  llvm.return
}
```
Translates to:
```llvm
define void @test(ptr %0) {
  %2 = getelementptr inbounds i8, ptr %0, i32 8
  %3 = load volatile double, ptr %2, align 8
  store double %3, ptr %0, align 8
  ret void
}
```

0 files changed, 0 insertions, 0 deletions