ClangCodeModel: Provide outline via clangd

Note that we used to encode the information about symbol visibility and
static-ness in the icons, which we can't do anymore, because clangd does
not provide this information.
On the upside, this change likely fixes a ton of bugs, as our own outline
was rather "quirky".

Change-Id: I099f11ec4e3c6f52cd461fb43080bbdde3bed5e5
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/languageclient/client.cpp

@@ -1003,6 +1003,16 @@ void Client::setDiagnosticsHandlers(const TextMarkCreator &textMarkCreator,
     m_diagnosticManager.setDiagnosticsHandlers(textMarkCreator, hideHandler);
 }
 
+void Client::setSymbolStringifier(const LanguageServerProtocol::SymbolStringifier &stringifier)
+{
+    m_symbolStringifier = stringifier;
+}
+
+SymbolStringifier Client::symbolStringifier() const
+{
+    return m_symbolStringifier;
+}
+
 void Client::start()
 {
     if (m_clientInterface->start())