Export MYSQL_UNIX_PORT to streamline CLI usage

[bhrutledge]

1. Driver: MySQL 5.7.23

2. DBngin build number: 3.1 (32)

3. macOS version: 10.15.7

Related to #38 and #52

Instead of using something like --socket=/tmp/mysql_3306.sock everywhere, it looks export MYSQL_UNIX_PORT=/tmp/mysql_3306.sock works (via the MySQL docs). Could you add that to "Export Environment Variable to Terminal", in addition to setting the PATH?

Thanks for making this!

[orientalperil]

Omg please put this in