[clang] [CIR] Support CoyieldExpr in emitLValue (PR #232298)

[Aman Maurya via cfe-commits]

amanmaurya92 wrote:

> Few things inline, the main one is doing `co_await` in the same go.

Sorry for splitting these changes across two PRs. I'll keep this one focused on `co_yield`, then rebase the `co_await` PR once this is merged. I'll keep related changes in a single PR going forward. Thanks for the feedback!

https://github.com/llvm/llvm-project/pull/232298