[llvm] [dsymutil] Add option to copy swiftmodules built from interface (PR #165293)

[Jonas Devlieghere via llvm-commits]

JDevlieghere wrote:

> FYI I plan to merge this patch tomorrow if no one else wants to take a look before then. The patch is simple and has tests, so I don't expect it to break anything.

Although I see where you're coming from, I feel obligated to point out that doing so wouldn't be in accordance with our [code review policy](https://llvm.org/docs/CodeReview.html#lgtm-how-a-patch-is-accepted), unless you got someone to LGTM it in the meantime. Plus all the reviewers were at the Developer Meeting so giving folks a bit more time seems appropriate. This is really @adrian-prantl's domain in dsymutil so I'd like him to sign off on it.

https://github.com/llvm/llvm-project/pull/165293