object fields can not be hidden

[JBGruber]

I thought at first that this was an amcat4client issue, but the browser shows me an internal server error. In the amcat logs the error is:

elasticsearch.BadRequestError: BadRequestError(400, 'mapper_parsing_exception', 'Mapping definition for [dfm] has unsupported parameters:  [meta : {amcat4_display_meta=0}]')

steps to reproduce:

1. run the actioncat example action: https://github.com/ccs-amsterdam/actioncat/tree/main#r-action-example-tidy-document-features
2. go to the web interface and try to hide the dfm field (Fields -> Show in article)

[vanatteveldt]

In fact, it's probably a good idea to move all these instance-level field settings to the system index rather than (ab)using the mapping. This would also hold for determining which fields should be hidden from the metareader