Update FieldableDatabaseStorageController::mapToStorageRecord() now that all field types have a schema

Problem/Motivation

Before enforcing all field types to declare a schema, FieldableDatabaseStorageController::mapToStorageRecord() had to rely on the property definitions of the field type to check if it can/should store multiple properties in an entity base table. That's not really correct (e.g. properties might be computed) and the storage controller should rely more on storage-related info/methods than typed data properties.

Proposed resolution

Change the getPropertyDefinitions() call to getFieldDefinition()->getColumns().

Remaining tasks

None.

User interface changes

None.

API changes

None.