Data Table Improvements

### Summary
As part of the fix to the ic-data-table select issue (#3897), several efficiency improvements were identified.

### 💬 Description

Currently whenever a row in a data table is selected or de-selected, the full row data is emitted for the current and selected rows. As part of #3897, each row was given an ID value. This could potentially be used to:

- Only report the row ID on select and de-select, rather than the full data set for the row.
- Have a separate function to emit the row data (or row ID data) for all selected rows, as this would only be needed on trigger, rather than every selection or de-selection.

### 💰 Use value
This would reduce the amount of information being emitted and make it easier for users to get the information about selections when they want it.

### 🚨 Urgency (low, medium or high)
Low

### Additional info
Tell us anything else useful to help us understand your suggestion.

Start by reviewing issue #3897 and the ic-data-table implementation to understand the existing selection events and row IDs. Determine the intended event API for selection changes versus retrieving all selected rows; done means the behavior and emitted data are clearly specified and implemented without emitting full row data on every selection change.

Written by the indexing model from the issue text.