Insertion is stored as integer in database.
Therefore cast boolean to integer.
Otherwise DataHandler might throw error as saved data type differs from
provided data type.
Still very simple, but can be improved in future updates.
E.g. add info regarding error, or deep link to single import log with
errors, etc.
To provide that, we need to add some more code, which is not necessary
yet.
Provide first basic import mechanism.
It already allows to import entities into TYPO3 database.
Three entities are supported.
Entities are configured through import configuration.
This can be created, viewed, and edited through backend module.
Imports are tracked and accessible from backend module.
Still this is basic.
Importing lists of entities is not supported.
Multiple languages is not supported, etc.
Relates: #8214
