[clang] [llvm] [HLSL] Implement the `reflect` HLSL function (PR #122992)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-debian` running on `gribozavr4` while building `clang,llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/16/builds/12395

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/SPIRV/opencl/reflect-error.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: not /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -verify-machineinstrs -O0 -mtriple=spirv64-unknown-unknown /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll -o /dev/null 2>&1 | /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll
+ not /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -verify-machineinstrs -O0 -mtriple=spirv64-unknown-unknown /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll -o /dev/null
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll
RUN: at line 2: not /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -verify-machineinstrs -O0 -mtriple=spirv32-unknown-unknown /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll -o /dev/null 2>&1 | /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll
+ not /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -verify-machineinstrs -O0 -mtriple=spirv32-unknown-unknown /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll -o /dev/null
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll
RUN: at line 3: not
+ not

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/122992