[Xcodeproj] Add suffix -Package to default scheme name
[Xcodeproj] Add suffix -Package to default scheme name

Doing this so this scheme name doesn't collide with autocreated schemes in case
name of a target or product is same as name of the package.

apple/swift-package-manager,JGiola/swift-package-manager,sschiau/swift-package-manager,vmanot/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager,JGiola/swift-package-manager,abertelrud/swift-package-manager,abertelrud/swift-package-manager,sschiau/swift-package-manager,sschiau/swift-package-manager,abertelrud/swift-package-manager,vmanot/swift-package-manager,vmanot/swift-package-manager,vmanot/swift-package-manager,sschiau/swift-package-manager,apple/swift-package-manager,JGiola/swift-package-manager,JGiola/swift-package-manager,apple/swift-package-manager,vmanot/swift-package-manager,abertelrud/swift-package-manager,JGiola/swift-package-manager,sschiau/swift-package-manager