ClangCodeModel: Move highlighting code into its own set of files

No functional changes.

Change-Id: If6e5da7e79bf39e564f0f38520ae088f76543642
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/plugins/clangcodemodel/clangcodemodel.qbs

@@ -42,6 +42,8 @@ QtcPlugin {
         "clangdqpropertyhighlighter.h",
         "clangdquickfixfactory.cpp",
         "clangdquickfixfactory.h",
+        "clangdsemantichighlighting.cpp",
+        "clangdsemantichighlighting.h",
         "clangeditordocumentprocessor.cpp",
         "clangeditordocumentprocessor.h",
         "clangfixitoperation.cpp",
@@ -56,6 +58,8 @@ QtcPlugin {
         "clanguiheaderondiskmanager.h",
         "clangutils.cpp",
         "clangutils.h",
+        "tasktimers.cpp",
+        "tasktimers.h",
     ]
 
     Group {