Changed $App.fireEvent('portal:navbar:appendSlot'), same to sidebar
- `portal:navbar:appendSlot` now append child to navbar
- `portal:navbar:defineSlot` define slot with new child (renamed `appendSlot` -> `defineSlot`)
- `portal:sidebar:appendSlot` now append child to sidebar
- `portal:sidebar:defineSlot` define slot with new child (renamed `appendSlot` -> `defineSlot`)