[CIR][CIRGen] Add alignment attribute to AtomicCmpXchg

[FantasqueX]

There is an alignment attribute in MLIR's LLVMIR Dialect

clangir/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td

Line 1880 in a7383c9

OptionalAttr<I64Attr>:$alignment,

When Clang builds IR, it adds an alignment automatically

clangir/clang/lib/CodeGen/CGBuilder.h

Lines 168 to 177 in a7383c9

	llvm::AtomicCmpXchgInst *
	CreateAtomicCmpXchg(Address Addr, llvm::Value *Cmp, llvm::Value *New,
	llvm::AtomicOrdering SuccessOrdering,
	llvm::AtomicOrdering FailureOrdering,
	llvm::SyncScope::ID SSID = llvm::SyncScope::System) {
	return CGBuilderBaseTy::CreateAtomicCmpXchg(
	Addr.emitRawPointer(*getCGF()), Cmp, New,
	Addr.getAlignment().getAsAlign(), SuccessOrdering, FailureOrdering,
	SSID);
	}

This PR does the same thing for ClangIR.

Closes: #1275

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[Lancern]

Thanks for improving. The code format checker is yelling; remember to reformat the code please.

[Lancern]

LGTM!

[FantasqueX]

Thanks a lot for helping my first PR for clangir.
Really appreciate for your quick and helpful review 😘@Lancern