[Request] Config option to reduce Mimic rate and Mimic Core drop chance

It'd be nice to add a config option for us to change the spawn rate / chance of opening a chest and having it be a mimic. The default chance rate seems to be a bit too common for my taste. As well as adding a configure for the chance of a mimic core dropping from a mimic.

I request this, as personally I'd like to have a lower chance for mimics appearing as well as their drop rate for mimic cores to make it feel more of a challenge to get the reward of having a mimic companion.