Farmworld Finn

BUR #40596 has been approved by @nonamethanks.

rename finn_mertens -> farmworld_finn

Finn Mertens is the canon full name of Finn the Human, not just this alternate version of him, so it doesn’t make sense for this alternate version to just be tagged by that name. The series refers to this character as Farmworld Finn to differentiate him from normal Finn.

Should Finn’s full name be aliased to Finn the Human? Since the tag currently refers to Farmworld Finn, the currently proposed alias should be made to change the tags, but it should then be unaliased, then aliased to Finn the Human.

The bulk update request #40596 (forum #349769) has been approved by @nonamethanks.

Changed to a rename because of the above reason.