BinariesServlet - Use handle node name as Content-Disposition filename by default

In the "JCR property name configuration" section [1], it says we can configure a custom jcr property name on hippo:resource node (e.g, "demosite:filename") if we want to specify content disposition filename header.
However, it's not really common to add a custom property there in most projects.
Therefore, I think it would be nice if it uses the handle node name by default for that (e.g, "example.pdf") when content disposition header is turned on.

BTW, if content disposition filename header is not enabled, sometimes the link could look very weird especially when the link is generated from a content-block resource link, showing the link node path, not the handle path.

[1] https://www.onehippo.org/10/library/concepts/images-and-assets/content-disposition.html