[clang] [clang][modules-driver] Add scanner to detect C++20 module presence (PR #145220)

[Chuanqi Xu via cfe-commits]

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@@ -577,6 +577,16 @@ def err_drv_reduced_module_output_overrided : Warning<
   "please consider use '-fmodule-output=' to specify the output file for reduced BMI explicitly">,
   InGroup<DiagGroup<"reduced-bmi-output-overrided">>;
 
+def remark_found_cxx20_module_usage : Remark<
+  "found C++20 module usage in file '%0'">,
+  InGroup<ModulesDriver>;
+def remark_performing_explicit_module_build : Remark<
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ChuanqiXu9 wrote:

I don't like the name "explicit module". It is confusing to me. Please change this to other names. e.g., "clang managed C++ modules build"

https://github.com/llvm/llvm-project/pull/145220