[llvm] [mlir] [Dwarf] Support `__ptrauth` qualifier in metadata nodes (PR #83862)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> Would be glad to see @JDevlieghere's and anyone else's interested feedback on the changes.
> 
> @MaskRay I've addressed your comments in [1adcade](https://github.com/llvm/llvm-project/commit/1adcade6f8d54d8e8ebebc52709e4b293450d117) - would be glad if you let me know if the fixes are OK.

Thanks. I'm trying to study this patch as I am not so familiar with debug info IR.

If you don't mind waiting a bit, waiting for @dwblaikie (another debug information code owner) could be useful.

https://github.com/llvm/llvm-project/pull/83862