[clang] [CIR] Add ASTVarDeclInterface for AST attribute access (PR #179825)

[Bruno Cardoso Lopes via cfe-commits]

bcardosolopes wrote:

### Merge activity

* **Feb 13, 12:51 AM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.com/github/pr/llvm/llvm-project/179825).


https://github.com/llvm/llvm-project/pull/179825