Add ability to register a @TypeDef or AttributeConverter globally for a type

### Feature description

Every place I use a custom type that I've pulled in from a library, I have to put `@TypeDef` on it. It would be nice to be able to register this once, or create a AttributeConverter bean, or possibly even re-use a TypeConverter.

Start by reviewing the existing @TypeDef, AttributeConverter, and TypeConverter entry points in Micronaut Data. Clarify whether global registration, an AttributeConverter bean, or TypeConverter reuse is required, then define tests that demonstrate registration for a library-provided custom type.

Written by the indexing model from the issue text.