For #36200, revisited project switching

[sgsteph]

• Extracted binding versions to edits in dedicated method
• Changed project switching so version binding can be called
• Removed direct setting of current project in processor.
• Added set_sg_project signal and slots

[raphaelmatto]

Looks good, Stéphane. Very readable. It looks like you fixed up the preselect input stuff too, that's great!