Context:

OPT-4597 renames the start/endDate filters in UI to "instance start/EndDate" filters. This rename should also be applied to the related structures in the BE and to the "type" field of said filter. Note that this will require FE adjustment so do not merge until FE ticket is also done. This also needs adjusted on confluence.

AT:

• instance start/endDate filter type is renamed to "instanceStartDate" and "instanceEndDate" to match UI and differentiate between instance and flownode date filters
• a migration is added to migrate existing filters
• instance start/endDate structures in BE are renamed respectively
• Confluence is adjusted accordingly