Fix-161 - Align rows of Params Panel and Timetrack Panel

- change reference to size by height
- add Dock_Curves::on_update_header_height( int header_height) member
- connect Dock_Curves::on_update_header_height to studio::LayerTree::signal_param_tree_header_height_changed
- update the Dock_Curves's widget_timeslider on update_header_height
- update comments