Adding startup parameters to Flight Service apps

Let users add command-line start-up parameters to any EXE service they launch from PERFLIGHT, so tools that require specific flags can be started in the right mode (for example, running GSX/FSDT's Couatl_Updater.exe with /SILENT /INSTALLMODE=TRUE for an unattended update). A simple optional "Launch parameters" field on the service — entered space-separated, just like a desktop shortcut or Steam launch options — will be saved with the service and applied every time it's launched, with no command-line knowledge required. The underlying launch system already supports passing arguments; this adds the missing UI so users no longer have to edit the database by hand.