Add support for global hotkeys

**Problem**
Hotkeys do not trigger when the focused element is an input or textfield.

**Suggestion**
Add opt in support for global hotkeys that fire even when focus is inside some input form/textarea. There are cases where certain shortcuts (e.g Ctrl+S to click save button, Ctrl+K to click a command palette) should work everywhere including when the user is typing in some textarea.

The feature is similar to [Mousetrap’s Global Bind](https://github.com/ccampbell/mousetrap/tree/master/plugins/global-bind).

#### Possible Implementation
Introduce a `data-hotkey-global` attribute:
```
Save
```

#### Related Work
https://github.com/github/hotkey/pull/48