[TECHNICAL-SUPPORT | March 25] LPS-45455, LPS-45459, LPS-45457

https://issues.liferay.com/browse/LPS-45455
https://issues.liferay.com/browse/LPS-45457
https://issues.liferay.com/browse/LPS-45459

Note: with the new API (#getLayoutRelativeURL) we have the ability to use relative URLs everywhere (where makes sense) in the future.

Note 2: I wish someones added meaningful javadoc for the methods in PortalImpl. I always get confused when I need to find out (from the code only) what these methods return in different use cases. :-) Could you bring this to other cores' attention?

Thanks Eduardo!