App alert rework

Created by: xkureck

Check the AlertComponent.

• This component we are using for showing alert (eg. No groups) when there is no item in the table or when filtering filters no items. Create for this new component. That component will just show the plain text in the middle of the screen in bold typing that eg.: "No groups founded".
• This component we are also using for INFO (eg. searching doesnt started yet, type something to search). In this case we would like also new component that will show the same information but without the blue colour.
• We are using this component also for ERROR - this is what we will use this component for. Dont change it.