[ClangOffloadBundler] fix unbundling archive (#84195)

When unbundling an archive, need to save the content of each object file
to a temporary file before passing it to llvm-objcopy, instead of
passing the original input archive file to llvm-objcopy.

Also allows extracting host bundles for archives.

Fixes: https://github.com/llvm/llvm-project/issues/83509