Integrate with Views Date Format SQL

Problem/Motivation

Visitors format a timestamp field to display certain reports. It would be better if this functionality was in another module to be reusable.

Steps to reproduce

Proposed resolution

Remove custom visitors date views plugins and replace with views_date_format_sql

Remaining tasks

🐛 PostgreSQL SQL Error: Undefined function FROM_UNIXTIME Active
🐛 NOT CORRECT DATE WITH TIMEZONE Needs work

User interface changes

API changes

Data model changes