kcms/color: fix tint inconsistency
The tinting does not work when using the accent color from wallpaper. This happens because till now accent color is being defined as something that is different from the default colorscheme accent color. Excluding the default accent color does not make sense. It is also an accent color. After all there can't be any good colorscheme without an accent color.
There's also has been a notion of a colorscheme having an accent color or not depending on the current definition of accent color. Based on this, there are several checks like hasAccent() which completely does not make sense. So they have removed.
Now also till now the hasAccent() check has been wrongly used to infere whether we have a default accent color or not, so that when copying one config to another, some modification operations can be saved. This kind of special provisions for sure will cause bug, and in fact already have caused this bug. We always should ,at least this is what I think, try to do things using a general algorithm and try to avoid special cases in the algorithm as much as possible. We currently can apply the whole accent using a single elegant way and just merely to save 1-3 modifications of config entries while tons of them are being already copied does not make sense. Now in this MR we take an accent color and just apply them and do not try to find what kind of accent color is given. If the color is transparent, we already know the color should be the default one (a convention that's being used already) and we pull out default accent color from colorscheme instead of doing some fancy special operations.