Introduce `--random-mac` and `--random-serial` flags for `tart set` (#809)

To generate new MAC address and/or serial number for a given VM.

Sources/tart/Commands/Set.swift

@@ -1,5 +1,6 @@
 import ArgumentParser
 import Foundation
+import Virtualization
 
 struct Set: AsyncParsableCommand {
   static var configuration = CommandConfiguration(commandName: "set", abstract: "Modify VM's configuration")
@@ -16,6 +17,14 @@ struct Set: AsyncParsableCommand {
   @Option(help: "VM display resolution in a format of <width>x<height>. For example, 1200x800")
   var display: VMDisplayConfig?
 
+  @Flag(help: ArgumentHelp("Generate a new random MAC address for the VM."))
+  var randomMAC: Bool = false
+
+  #if arch(arm64)
+    @Flag(help: ArgumentHelp("Generate a new random serial number for the macOS VM."))
+  #endif
+  var randomSerial: Bool = false
+
   @Option(help: ArgumentHelp("Resize the VMs disk to the specified size in GB (note that the disk size can only be increased to avoid losing data)",
                              discussion: """
                              Disk resizing works on most cloud-ready Linux distributions out-of-the box (e.g. Ubuntu Cloud Images
@@ -51,6 +60,17 @@ struct Set: AsyncParsableCommand {
       }
     }
 
+    if randomMAC {
+      vmConfig.macAddress = VZMACAddress.randomLocallyAdministered()
+    }
+
+    #if arch(arm64)
+      if randomSerial {
+        let oldPlatform = vmConfig.platform as! Darwin
+        vmConfig.platform = Darwin(ecid: VZMacMachineIdentifier(), hardwareModel: oldPlatform.hardwareModel)
+      }
+    #endif
+
     try vmConfig.save(toURL: vmDir.configURL)
 
     if diskSize != nil {