[clang] [CIR] Add CxxCTorAttr, CxxDTorAttr, CxxAssignAttr, CxxSpecialMemberAttr to cir::FuncOp (PR #167975)

[Henrich Lauko via cfe-commits]

xlauko wrote:

> > In general it would be nice to have more helper methods on operation and attributes like `isCtor`, `isMoveCtor` etc.
> 
> Should I add this to the `extraClassDefinitions` of `FuncOp` in CIROps.td?

Yes, that would be probably best.

https://github.com/llvm/llvm-project/pull/167975