[llvm] [DwarfDump] Add new set of line-table-related statistics to llvm-dwarfdump (PR #93289)

[Stephen Tozer via llvm-commits]

SLTozer wrote:

> Do we need any more targeted tests for the stats (for example, exercising the cu-unique-file-id code you added)?

Could add a second test that uses multiple compile units - not sure what the best way to handle that is, but I'm sure there'll be some existing lit examples I can base it on.

https://github.com/llvm/llvm-project/pull/93289