/reviewed-on klaus/wendelin!2

Data Bucket Stream is usefull when storing data from many small files

/reviewed-on klaus/wendelin!1

This solves the previous commit problem.

TODO: the test

If the Data Ingestion is not found with catalog, searching by ID is the fallback.
We need to check the validation_state even if it is searching by the ID.

This allows to set all kinds of arrow properties while keeping the main view simple.

The previous implementation did not support saving categories in view form.
It is better to use standard Base_edit in view forms and put actions which are other than "save"
into a dialog.

getArrayDtype can be used for example by html5 app to display graph with correct dtype

data model: split ingestion policy script (tag parsing) form ingestion operation (writing to data stream)