[REG 5.10->5.11.0] When using QDir with an assets-library path then it can end up not seeing it as absolute

When using QDir().absoluteFilePath("assets-library://foo") then it will treat it as being relative to the local file system and return an incorrect path. This goes against the Qt 5.10 behaviour where it was not doing this. Although it is arguably expected, it is used in this manner too much and the Qt resource case is already accounted for.