[llvm] [llvm][object] Expose `writeArchiveToStream` (PR #98254)

[James Henderson via llvm-commits]

jh7370 wrote:

No, I'm fine with the change actually (though I'd consider whether there's a way of having in-tree tests), but usually if you're putting something up for review, you don't immediately merge it into main before anybody has a chance to give that input, while if you think it doesn't need pre-commit review, you just push it directly without creating a PR, so I'm questioning the process you've gone through rather than the change itself.

https://github.com/llvm/llvm-project/pull/98254