Add checkbox in workflow UI for Autoclick behavior

[tw4l]

Once we have Autoclick as an option (see crawler PR webrecorder/browsertrix-crawler#729), we'll need a way in the Browsertrix UI to enable it.

We should also make sure that checking this option doesn't cause the crawler to fail if using an older crawler release channel that doesn't have autoclick.

[ikreymer]

Probably simplest way is to add a filter to remove autoclick when creating ConfigMap in _load_crawl_configmap(). Maybe we should make crawler ignore unknown behaviors, rather than fail out in next release also.