ClangCodeModel: Take changes from header files into account immediately

... in the dependent sources. That's also how the built-in code model
behaves, but clangd itself only does this when a document is saved.

Change-Id: I52d6badb0b7f063e5924c05dbf83a6e9849c9f6f
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangcodemodelplugin.cpp

@@ -90,6 +90,7 @@ void ClangCodeModelPlugin::initialize()
     addTest<Tests::ClangdTestFindReferences>();
     addTest<Tests::ClangdTestFollowSymbol>();
     addTest<Tests::ClangdTestHighlighting>();
+    addTest<Tests::ClangdTestIndirectChanges>();
     addTest<Tests::ClangdTestLocalReferences>();
     addTest<Tests::ClangdTestTooltips>();
     addTest<Tests::ClangFixItTest>();