[llvm] [nfc][thinlto] Factor common state for `computeImportForModule` (PR #65427)

[Teresa Johnson via llvm-commits]

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@@ -370,6 +370,29 @@ class GlobalsImporter final {
   }
 };
 
+/// Determine the list of imports and exports for each module.
+class ModuleImportsScheduler final {
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teresajohnson wrote:

Why "Scheduler"? To me that term means that ordering is important, and it isn't for importing. Maybe "Helper" or "Manager"?

https://github.com/llvm/llvm-project/pull/65427