[llvm] [llvm/llvm-project][Coroutines] Move spill related methods to a Spill utils (PR #107884)

[Tyler Nowicki via llvm-commits]

TylerNowicki wrote:

> I didn't check if they are strictly the same line by line. But I believe it is trivial code movement. So LGTM with removing the prefix `[llvm/llvm-project]`.
> 
> But it looks like there were some regression reports for the first issue. Please take a look before landing.

Looks like the test failure is due to a permissions issue.

"C:\a\lld-x86_64-win\llvm-project\llvm\unittests\Support\ProgramTest.cpp(163): error: fs::remove(Twine(LongPath)): did not return errc::success.
error number: 13
error message: permission denied"

https://github.com/llvm/llvm-project/pull/107884