Single Barefoot to Single Bare Foot

BUR #557 has been approved by @Lyren.

create alias single_barefoot -> single_bare_foot

Consistency with Dan, as this tag is also single bare foot on there.
https://danbooru.donmai.us/wiki_pages/single_bare_foot

The bulk update request #557 (forum #3391) has been approved by @Lyren.