Handling of mixed string and 0 broken for keepItems and removeItems page ts
When having a field in TCA which has items with integer values and string values, then it is not possible
to reliably remove the item with "0" value.
When using keepItems=foo, the item with value "0" will stay.
When using removeItems=foo, the item with value "0" will also be removed
This can be tested with news extension and the type field, which holds integer values (including 0) for default news
and string values, when news is extended.
TCEFORM.tx_news_domain_model_news.type.removeItems = CustomNewsType
will also remove default news type (which is 0)
TCEFORM.tx_news_domain_model_news.type.keepItems = CustomNewsType
will NOT remove default news type