LanguageClient: Allow to log to console rather than message window

And make use of that in ClangdClient.
When I get a slowdown while typing, it is usually accompanied by the
clangd message "Request cancelled because the document was modified"
occurring in the message window, often many times in a row. I'd like to
find out whether writing to the message window itself is a contributing
factor to the slowdown.

Change-Id: Iff7c459af0aed27d22366b9aade573f51eb5dbc7
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.cpp

@@ -1081,6 +1081,7 @@ ClangdClient::ClangdClient(Project *project, const Utils::FilePath &jsonDbDir)
             "text/x-c++hdr", "text/x-c++src", "text/x-objc++src", "text/x-objcsrc"};
     setSupportedLanguage(langFilter);
     setActivateDocumentAutomatically(true);
+    setLogTarget(LogTarget::Console);
     setCompletionAssistProvider(new ClangdCompletionAssistProvider(this));
     if (!project) {
         QJsonObject initOptions;