[llvm] [llvm][dwarfdump] Add --child-tags option to filter by DWARF tags (PR #165720)

[Adrian Prantl via llvm-commits]

adrian-prantl wrote:

I would have probably called it `--filter-child-tag` and @dwblaikie 's question about the query language resonates with me. OTOH, dwarfdump is presumably primarily used by us LLVM developers so why not add a few bespoke features that benefit us?

https://github.com/llvm/llvm-project/pull/165720