[redux-slider-monitor] Allow overriding keyboard hotkeys via props

[okorz001]

redux-slider-monitor should allow configuring hotkeys like redux-devtools-dock-monitor using parse-key.

Currently the key codes are hardcoded: https://github.com/reduxjs/redux-devtools/blob/master/packages/redux-slider-monitor/src/SliderMonitor.js#L83-L104