Add 'printable' option for parts of a split object

[DECO74]

Is your feature request related to a problem? Please describe.
In some cases, when you have a multi-material project to print, you have to split the object into objects, when you do this, the objects get dropped to the bed and looses it's Z reference. In a non-multimaterial printer where the process is done manually, keeping the object in it's original position is key to printing sucessfully.

Describe the solution you'd like
Enable the 'printable' switch for parts of a split into parts object. This way we can choose which parts of the object we need to print.

Describe how it would work
First you split your objects to parts, As in the object which we can click the printable column (indicated by the eye icon), it must be choosable which part of the object we want to print or not. Or right clicking on the part of the object in the objects list, will bring the context menu, in which will have the Printable option to click. The user must be warned that it must ensure that his printing process is feasible.

Describe alternatives you've considered
The alternative solution is the one I use today, which is splitting the objects in objects. I then prepare the number of prints I will send, adjusting the z-offset of the printer manually for each print.

Additional context
**This option should be made available in the advanced settings only.
**The user must be warned and aware that the usage of this options must be done wisely, as the slicer can't control human manipulation and production processes.