Implementation of `methods.RenameSnapshot` for `VirtualMachineSnapshot` in simulator

[Joshzxj]

Is your feature request related to a problem? Please describe.
I would like to use gomomi to operate snapshot renaming. I know currently gomomi supports renaming

import "github.com/vmware/govmomi/vim25/methods"
...
	// Create rename request
	req := types.RenameSnapshot{
		This: snapshotRef,
		Name: newName,
	}

	// Execute rename operation
	_, err = methods.RenameSnapshot(vp.ctx, vcClient.VimClient, &req)
	if err != nil {
		return fmt.Errorf("failed to rename snapshot %s to %s: %w (request: %+v)", snapshotRef.Value, newName, err, req)
	}

But I am not able to mock in our test using the same code. That is because vcsim doesn't support implement this methods.(methods.RenameSnapshot throws "does not implement: RenameSnapshot")

Describe the solution you'd like
Looks like VirtualMachineSnapshot simulator needs to implement above method in https://github.com/vmware/govmomi/blob/main/simulator/snapshot.go

Currently, the method is missing.
https://pkg.go.dev/github.com/vmware/govmomi@v0.52.0-alpha.0.0.20250707220414-858de8d6c62a/simulator#VirtualMachineSnapshot

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