Issue title: Hide splitter
 Issue body: I have 2 panes with vertical splitter. I have a toggle button to expand / restore first pane to full / original width. It does this by setting the splitpanes 'size' prop. Works well. However I need to hide the splitter in the expanded state and show it in the restored state. Is there a way I can do this? Thanks.
 Comments: 
 Comment 0: Hi @edbotdev, I would do this via CSS.
Please share a reproduction link so I can help you.
Please reopen if not solved.
{'source': 'GithubIssues', 'repo_name_with_owner': 'antoniandre/splitpanes', 'issue_id': 1160580705, 'repo_stars': 1164.0}