[clang] [clang][Dependency Scanning] Report What a Module Exports during Scanning (PR #137421)

[Qiongsi Wu via cfe-commits]

================
@@ -115,6 +115,15 @@ struct ModuleID {
   }
 };
 
+struct ExtendedModuleID {
----------------
qiongsiwu wrote:

Hmmm I think I am misunderstanding something. Is this what we are proposing? Instead of 
```
  std::vector<ModuleDeps::DepInfo> ClangModuleDeps;
```

we have

```
  std::vector<std::pair<ModuleID, bool>> ClangModuleDeps;
```

It feels like using pairs is less expressive than naming the two fields in `DepInfo`. 

https://github.com/llvm/llvm-project/pull/137421