Property group aliases lead to serialization mis-matches when using uda files created from previous versions #92
Description
When schema files, created from older versions, are read from disk and deserialized into artifacts, these can differing from the artifact representations read from the database. For most introduced properties this isn't an issue, as the default value obtained when deserialising from the .uda file when a property is missing matches the empty value retrieved from the database when the property isn't set (e.g. false for boolean, 0 for integer).
This isn't the case for property group aliases though, introduced in CMS 8.17. Specifically the alias of the property group had a default value set based on the name (in 8.17), or was empty string for older CMS versions, both of which differed when compared to the null value found from a .uda file serialized on a version of Deploy before tabs were introduced.
To resolve we need to sets the appropriate value after reading from the .uda files, so that these comparisons now can correctly determine a doc type serialized from an older version of Deploy hasn't changed when comparing to an installation running the latest version.