[clang] [clang][Sema] Propagate `volatile` during derived-to-base conversion (PR #127824)

[Antonio Frighetto via cfe-commits]

antoniofrighetto wrote:

> Should the result type of the ImplicitCastExpr be volatile in the AST?

Definitely, updated, thanks!

https://github.com/llvm/llvm-project/pull/127824