[clang] [clang][Modules] Make `Module::Requirement` a struct (PR #67900)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

> Would someone be able to merge this for me? I do not have permission.

Sorry for not merging this in time. Could you rebase again since it has conflicts now.

https://github.com/llvm/llvm-project/pull/67900