[llvm] [Support] Introduce formatv variant of createStringError (PR #80493)

[Craig Topper via llvm-commits]

topperc wrote:

I don't know what all your use cases are but for that specific example you can write `createStringError(..., "Something went wrong: " + Foo);` which uses the Twine version.

https://github.com/llvm/llvm-project/pull/80493