QmlJSEditor: jump to file under cursor if it exists

Don't limit this functionality to files that are part of the snapshot,
but try to open all files. This will allow opening c++ files defined in
a qbs project file.

Fixes: QTCREATORBUG-22685
Change-Id: If2a2a2075e5d7113a7bb44625c0f29ef66138d3c
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/qmljseditor/qmljseditor.cpp

@@ -791,7 +791,7 @@ void QmlJSEditorWidget::findLinkAt(const QTextCursor &cursor,
         const QString relative = QString::fromLatin1("%1/%2").arg(
                     semanticInfo.document->path(),
                     text);
-        if (semanticInfo.snapshot.document(relative)) {
+        if (QFileInfo::exists(relative)) {
             link.targetFileName = relative;
             processLinkCallback(link);
             return;