Sets the collision mask for this Game Object's Matter Body. Two Matter Bodies with different collision groups will only
collide if each one includes the other's category in its mask based on a bitwise AND, i.e.
(categoryA & maskB) !== 0
(categoryB & maskA) !== 0 are both true.
|categories||number | Array.<number>||
A unique category bitfield, or an array of them.
This Game Object.