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>
Please add new tests to https://github.com/alexeykazakov/jbosstools-base/tree/master/common/tests/org.jboss.tools.common.core.test/src/org/jboss/tools/common/core/test/WebUtilsTest.java for this method.