[CIR][X86] Implement lowering for sqrt builtins (#169310)
Implements CIR IR generation for X86-specific sqrt builtin functions,
addressing issue #167765.
## Test Results
Successfully tested the implementation locally. All tests pass:
```bash
$ ./bin/llvm-lit -v ../clang/test/CIR/CodeGen/X86/cir-sqrt-builtins.c
Testing: 1 tests, 1 workers
PASS: Clang :: CIR/CodeGen/X86/cir-sqrt-builtins.c (1 of 1)
Testing Time: 1.18s
Total Discovered Tests: 1
Passed: 1 (100.00%)
```
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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Andy Kaylor <akaylor@nvidia.com>
