Frontend: teach -compile-module-from-interface action to emit ABI descriptor as byproduct

We have implemented a libSwiftDriver-based tool to generate prebuilt module cache for
entire SDKs. Anchored on the same infrastructure, we could also generate ABI baselines
for entire SDKs.

lib/Frontend/ModuleInterfaceBuilder.cpp

@@ -284,6 +284,9 @@ bool ModuleInterfaceBuilder::buildSwiftModuleInternal(
     if (SubInstance.getDiags().hadAnyError()) {
       return std::make_error_code(std::errc::not_supported);
     }
+    if (!ABIDescriptorPath.empty()) {
+      swift::ide::api::dumpModuleContent(Mod, ABIDescriptorPath, true);
+    }
     return std::error_code();
     });
   }, ThreadStackSize);