Deleting floppy images on teardown

[pragmaspark]

fixes #137

[mkuzmin]

Can we get the filename from the state instead of hardcoding it?
https://github.com/jetbrains-infra/packer-builder-vsphere/blob/master/iso/step_remove_floppy.go#L33

[pragmaspark]

No. Because we could be faced with a situation: when the file uploaded, but the state not have information about uploadPath.

packer-builder-vsphere/iso/step_add_floppy.go

Lines 42 to 47 in a00a2ad

	uploadPath := fmt.Sprintf("%v/packer-tmp-created-floppy.flp", vmDir)
	if err := ds.UploadFile(floppyPath.(string), uploadPath); err != nil {
	state.Put("error", err)
	return multistep.ActionHalt
	}
	state.Put("uploaded_floppy_path", uploadPath)

[mkuzmin]

then that's not our business. If govmomi returns an error during uploading, it should handle cleanup by itself.

[mkuzmin]

don't need this check

[mkuzmin]

there are two styles

ds, err := d.FindDatastore(s.Datastore, s.Host)
if err != nil {

and

if err := ds.Delete(UploadedFloppyPath.(string)); err != nil {

we mostly use the 1st.