[Enhancement] Custom columns in table widget cannot reference other custom columns from currentRow

## Description

In the table widget, custom column can refer to other column values of the current row using bindings like `{{currentRow.columnName}}`. However, when using this to refer to other custom columns, the value always returns `null`.


If using other computed columns is not supported, then they should be removed from the auto-complete suggestions, or it gives the wrong impression that they can be used.

### Steps to reproduce the behaviour:

1. Drop a new table widget.
2. Add a new column, the `customColumn1`, and set it's computed value to `{{currentRow.step + 'x'}}`. Notice that the values in this column show up correctly.
3. Now add another column, the `customColumn2`, and set it's computed value to `{{currentRow.computedColumn1}}`.
4. Notice that the value in this column is always empty.

### Important Details

- Version: Cloud
- OS: macOS
- Browser: Firefox
- Environment: Production, .