upgrade/24.09.1, convert-entity: adds entity-types-php@2 mixin even the extension doesn't define new entities

[semseysandor]

\CRM\CivixBundle\Command\ConvertEntityCommand::convertEntities() is called regardless if there are actual legacy xml entities to convert, and it adds the entity-types-php@2 unconditionally.

In this PR, convertEntities is called only if there are files to convert. Also a check is
added to convertEntities to return early if it's called with no xml files.

fixes #372

[totten]

Seems good to me.

I played with running the upgrade on a few different extension scenarios, eg

• Ext with no schema/upgrader/etc;
• Ext with custom upgrader... but no EFv1 metadata
• Ext with full EFv1 (upgrader/sql/metadata/etc)

Where it changed, it all seemed to change for the better. 👍

Thanks @semseysandor!

[colemanw]

Great work @semseysandor !