ClangCodeModel: Handle UI header updates with clangd

We need to manually refresh the documents that include the generated
header, as clangd does not know about it.

Change-Id: I8c4303ac029bbb56c01aa99b7950dcc651701678
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.h

@@ -86,6 +86,8 @@ public:
     static QString displayNameFromDocumentSymbol(LanguageServerProtocol::SymbolKind kind,
                                                  const QString &name, const QString &detail);
 
+    static void handleUiHeaderChange(const QString &fileName);
+
 signals:
     void indexingFinished();
     void foundReferences(const QList<Core::SearchResultItem> &items);