[FEATURE] Randomize Splash Screen Background

[Coding-Sock]

Is your feature request related to a problem? Please describe.
N/A

Describe the solution you'd like
A feature where you can specify a custom directory for the splash screen background video.
If a folder is specified, it will pick a random background video from the folder when displaying the splash screen.
If you specify a specific file, you could leave behavior as it is now where just that specific background video will play.

Describe alternatives you've considered
N/A - Could make multiple bats but it requires restarting pikaraoke each time

Additional context
N/A