Settings: rename the member/settings subnav tab name from "Profile" to "Profile Visibility".

The new name clarifies what the purpose of this subnav screen is; that is, to manage profile fields' visibility.

Fixes #5599, props tharsheblows

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9167 cdf35c40-ae34-48e0-9cc9-0c9da1808c22