ClangCodeModel: Provide tooltips via clangd

Note that we temporarily lose the ability to hover over an include and
get the full path of the header file. This is a valuable feature that we
need to restore, preferably by fixing clangd itself.
Fixing the remaining few test failures would likely require more
complicated code as well as additional LSP round-trips, and as of now
I'm not convinced it is worth the effort.

Change-Id: I08c72c4bd1268bbd67baeb57bbfd29d9b11303a5
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/texteditor/texteditor.cpp

@@ -5778,6 +5778,13 @@ void TextEditorWidget::removeHoverHandler(BaseHoverHandler *handler)
     d->m_hoverHandlers.removeAll(handler);
 }
 
+#ifdef WITH_TESTS
+void TextEditorWidget::processTooltipRequest(const QTextCursor &c)
+{
+    d->processTooltipRequest(c);
+}
+#endif
+
 void TextEditorWidget::extraAreaLeaveEvent(QEvent *)
 {
     d->extraAreaPreviousMarkTooltipRequestedLine = -1;