Individual group resize within layout

[ktbacher]

• [*] I am requesting a new feature

Description of requested feature
The current continuous resize for individual charts doesn't work within the layout concept and there is currently no way to have groups larger than 1 unit cell size in the layout. For this feature, a new mechanism to allow resizing a group in a layout by an entire row or column size, likely by changing the group size update to be defaultGroupSpacing + lyra_layout_X_col_Y_size (and same for row).