Make the API return a beatmap's lazer max combo

[TTTaevas]

Currently, the max combo you can get on a beatmap is different depending on if you're playing on stable or on lazer (without classic mod) For example, on this beatmap, the max combo is 2106x on stable, but it's 1465x on lazer

I believe it would be useful to have the max combo possible on lazer as well through the API, for example on BeatmapCompact as max_combo_exp (it's worth noting UserStatistics has something similar for a user's lazer rank and pp, global_rank_exp and pp_exp respectively, even if they're not featured in the documentation)