RTE filters do not work and break da-universal

We need support for RTE filters to downfilter aka. remove options from RTE. A filter like below breaks da-universal.

```
"filters": [
{
"id": "hero",
"rte": {
"format": [
"bold",
"italic",
"underline"
],
"alignment": [],
"indentation": [],
"sr_script": [],
"list": [],
"insert": [],
"advanced": [],
"extensions": [],
"editor": [],
"blocks": []
}
}
]
```

Start by reproducing the RTE filter example from the issue and trace how the filter is handled in da-universal. Verify that the listed RTE options are removed without breaking da-universal, and add or update regression coverage if the relevant test area is found.

Written by the indexing model from the issue text.