ilike/nilike on ESS's federated endpoint

[anne-pc]

Is your feature request related to a problem? Please describe.
I want to use the ilike operator as default for text field search. Currently not working as expected.
Describe the solution you'd like
I'd love it to work as their like/nlike couterparts but with the case-insensitiveness
Describe alternatives you've considered
If a specific query language will be required to do that, it can be added as middleware to the frontend adapter. Please don't.
Additional context
Add any other context or screenshots about the feature request here.