[clang] [clang][ASTImporter] IdentifierInfo of Attribute should be set using 'ToASTContext' (PR #73290)

[Qizhi Hu via cfe-commits]

jcsxky wrote:

> I think it is better to add the import of AttrName to the attribute import code (function `Import(const Attr *FromAttr)` and what is called from it). Probably it works to add it to `AttrImporter::cloneAttr` and do it like `const IdentifierInfo *ToAttrName = Importer.Import(FromAttr->getAttrName());`.

Fixed according to your guidance.

https://github.com/llvm/llvm-project/pull/73290