[llvm] [AsmPrinter][DebugNames] Implement DW_IDX_parent entries (PR #77457)

[Felipe de Azevedo Piovezan via llvm-commits]

felipepiovezan wrote:

Pushed two fixups: one with the NFC changes requested, one changing IDX_Parent so that it is not included when the parent is a forward declaration (see the test added with that commit)

https://github.com/llvm/llvm-project/pull/77457