Improve "Delete saved event"

[marcel263]

Describe what you are trying to accomplish and why in non technical terms
Improve "Delete saved event?" screen. Right now it cannot be closed by clicking or keyboard action. This is a problem for devices without access to browser refresh function.

Describe the solution you'd like
Implement "cancel" button or right click to close overlaid screen.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Frigate 0.12.1-367d724 Firefox