`GridModel.restoreDefaults` should respect latest colConfigs

[ghsolomon]

GridModel.restoreDefaultsAsync currently restores the original colConfigs specified at construction-time:
https://github.com/xh/hoist-react/blob/develop/cmp/grid/GridModel.ts#L531

However, it is possible to call setColumns with a new list of colConfigs, in which case the expected behavior would be for restoreDefaultsAsync to restore that collection of columns.

The current behavior is particularly problematic when columns that no longer exist are restored.

[lbwexler]

Hi @ghsolomon -- would love to discuss this one. Think it might clarify if you could show me the client app in which you ran in to this problem

[ghsolomon]

Screenshot showing issue in Toolbox.

restore-defaults-bug.mov

1. setColumns is called with a new set of columns without the "City" column.
2. As expected, the "City" column is removed from the Grid and no longer appears in the ColumnChooser. At this point there is no way for the user to bring it back, unless...
3. The user clicks "Restore Defaults". Then the "City" column reappears and is once again available in the ColumnChooser.