Connected PCB Component

You are given a $2$ D grid of size $mn$ representing a PCB where each cell is either unsoldered $($O$)$ or soldered $(1).$ The cells are connected horizontally and vertically $($and diagonally$).$

Your task is to find the size of the largest connected component of soldered cells on the PCB$.$

Example:

Input:

$1,0,0,1$

$1,0,0,0$

$1,1,0,1$

$0,0,1,0$

Output: $6$