JBIDE-17849 CSS Hyperlinks aren't working on non-WTP projects

An utility helper method is added due to find pages in projects that are not the WTP ones
(has no web-roots that can be achieved by WTP methods)

Signed-off-by: vrubezhny <vrubezhny@exadel.com>
But It looks like I've found the case when findResource() fails to find a file that exists in project. The case comes from Dynamic Web Project and the resolver that returns a correct full absolute path string for the CSS Stylesheet, but because it's full path (from the devce root) it cannot be resolved correctly by findResource method. So, I've improved the method for this case.