Frontend notification improvements

[jordy2254]

Describe the bug
Found in PR #892 was a bug with overflowing of long notifications. Additionally error notifications as marked by the backend do not appear to display differently in the UI, Having a different coloured background for success and failure would be beneficial for easily distinguishing the difference when using the system.

To Reproduce
cause a media scan error on an unsuitable format file.

Expected behaviour
The notification clearly indicates its an error and doesn't overflow

Screenshots
If applicable, add screenshots to help explain your problem.

Your environment:
N/A

[kkovaletp]

a screenshot: