Fixed custom field transliteration

[snipe]

We're seeing an issue in certain cases where PHP has been upgraded that can result in a 500 error when adding/updating an asset, because what we're expecting that column to be named and what it's actually named are now different, due to (what we think is) a small change in the PHP transliteration library.

This PR updates the existing snipeit:regenerate-fieldnames console command to check both the column name on the assets table and also the value in the db_column field in the custom_fields table.

You can tell if this script will fix your issue by going to the Custom Fields page in your UI, disclosing the "DB Column" column using the column selector, and then looking for warning text.

Output of the console log looks like this:

[uberbrady]

This looks even better - nice work!