Expose a custom row model API, similar to custom features

[lydphillips17]

Hello,

My team has been experimenting with the custom features API. It's proven to be very easy to interact with when adding our features on top of the existing table instance APIs.

We would like to implement our own custom rowModel as well, but this is not currently supported and the only option is to fork the code.

Would it be possible to introduce an API that enables consumers to define their own rowModel, similar to how custom features work?