Apple Virtualization: only update shared directories if they changed to avoid unnecessary virtiofs reconnections

For Apple Virtualization, only update shared directories if they changed to avoid unnecessary virtiofs reconnections.

Although this issue existed prior to v4.5.4, following v4.5.4, UTM introduced dynamic resolution.  Resizing
the window with dynamic resolution is one repeatable way to cause a registry update.  updateConfigFromRegistry()
updates the shared directories on every call, causing the virtiofs to reconnect.  As the virtiofs disconnects
and reconnects, file and directory handles on the share are invalidated causing guest application errors.

To reproduce bug:
- Apple Virtualization, Linux guest, Dynamic resolution enabled
- Open terminal
- $ cd {shared_directory}
- Resize the window
- $ ls
- Result: ls: cannot open directory '.': No such file or directory

Author: evan314159

Services/UTMAppleVirtualMachine.swift

@@ -968,7 +968,18 @@ extension UTMAppleVirtualMachine {
     }
 
     @MainActor func updateConfigFromRegistry() {
-        config.sharedDirectories = registryEntry.sharedDirectories.map({ UTMAppleConfigurationSharedDirectory(directoryURL: $0.url, isReadOnly: $0.isReadOnly )})
+        // Only update shared directories if they actually changed to avoid unnecessary virtiofs reconnections
+        let newShares = registryEntry.sharedDirectories.map({ UTMAppleConfigurationSharedDirectory(directoryURL: $0.url, isReadOnly: $0.isReadOnly )})
+
+        let sharesChanged = newShares.count != config.sharedDirectories.count ||
+            zip(newShares, config.sharedDirectories).contains { new, old in
+                new.directoryURL != old.directoryURL || new.isReadOnly != old.isReadOnly
+            }
+
+        if sharesChanged {
+            config.sharedDirectories = newShares
+        }
+
         for i in config.drives.indices {
             let id = config.drives[i].id
             if config.drives[i].isExternal {