Automations / Scriptable actions
### Current Situation

Lacks support for actions / triggers / scripts


### Proposed Change

Include an API? or other methods of controlling home bridge accessories programatically, either internally or externally.

### Additional Context

1st of all, thank you for home bridge! I've been using it for years on various devices and configs (hw / VM / Qemu + Mac / RPi) and it's been mostly awesome. There are a few things (hue lights for example) where I use homeassistant as an alternative for automation / scripting etc. that I'd love to dump for home bridge if it supported actions / scripts etc.

Anyway, just my 2cs. Thanks again, keep up the good work!