* Convert StatusBarRegistration to use components field

- More similar to all other *Registration types for extensions

- Simpler fix for using the components.Icon type, now accepts functions
  that return component instance like all other *Registration types

- Kept old fix for backwards compatability
Signed-off-by: Sebastian Malton <sebastian@malton.name>

* fix docs
Signed-off-by: Sebastian Malton <sebastian@malton.name>