Exclude file from backup and set data protection key

secureFilesystemItems.swift

extension FileManager {
    public func secureFilesystemItems(_ url: inout URL) throws {
        try (url as NSURL).setResourceValue(URLFileProtection.completeUntilFirstUserAuthentication, forKey: .fileProtectionKey)
        try (url as NSURL).setResourceValue(NSNumber(true), forKey: URLResourceKey.isExcludedFromBackupKey)
    }
}