cloning entities that have an extension in its name (".") should be named differently

[bjrmatos]

right now, in order to create the name of a cloned entity, the default behaviour is to append the "(clone)" string to the name of the original entity, this presents a problem for entities like the assets, where the extension part of the name is very important. so we should change the logic to consider this special case, and add the "(clone)" part before the "."

example:

"entity-name.css" -> "entity-name(clone).css"