[Installer] Verify case of 'Host' key while installing schema

[driusan]

While running the installdb part of the install process, I got the error "Could not retrieve hostname for MySQL user" when it tries to create the user.

This seems to have been caused by the fact that the key for the hostname in $connectHost was 'host' while what was coming back from the PDO query was 'Host'. This is unusual since the query is "SELECT host FROM" .. (lowercase). After changing the capitalization in the code the install proceeded normally.

It needs investigation to figure out if this is common or if there's a way to support both. (Maybe adding as host to the query?)

MariaDB 10.5.8, PHP 8.0.3