Replace remaining usages of old connect syntax with new connect syntax
This change replaces the remaining usages of the old connect syntax with the new connect syntax.
Unfortunately, there are still places where we have to use SIGNAL() and SLOT() macros, for example the stuff that deals with d-bus business.
Clazy was used to create this change. There were a few cases that needed manual intervention, the majority of those cases were about resolving ambiguity caused by overloaded signals.