[clang] [C++26] [Contracts] Support Parser, AST and AST Serialization (1/n) (PR #205739)

[Corentin Jabot via cfe-commits]

cor3ntin wrote:

> I didn't know it unluckily. If it is already tested well and Eric is not working on it, I'd like to take it.

That seems like a great path forward

https://github.com/llvm/llvm-project/pull/205739