refactor(handlers): refactor handlers to allow plugins development

[willianrod]

What's new

• New handlers engine
• Handlers are automatically registered
• Add handlers config store
• Handlers config page
• Show on sidebar only handlers active
• Add about page
• Improve UX while editing the device (resizable panels added)

How the new handlers engine works?

Now each handler registers itself automatically. During initialization each handler starts listening for keys events. They can listen to it's own event or you can also listen to events to other listeners too. This gives us a lot of flexibility, and you can even have a handler that plays a sound on every website opened. Or an April fools day handler that when pressing any keys, has 1% chance of opening of opening the rick roll video.

There is also a new handler config mechanism too, that allows developers to specify what should be configurable in their handler (example: API Key). You can even say that the config is secret so you can only write it, and cannot read it from client side.

If a plugin is not initialized (active), they are hidden from the sidebar

Screenshots