1905. Count Sub Islands

You are given two m x n binary matrices grid1 and grid2 containing only 0's (representing water) and 1's (representing land). An island is a group of 1's connected 4-directionally (horizontal or vertical). Any cells outside of the grid are considered water cells. An island in grid2 is considered a sub-island if there is an island in grid1 that contains all the cells that make up this island in gr