Add option to use Plex Servername instead of "Plex"

[prueckls]

Description

It would be great to have an option in the dashboard to change the generic 'Plex' name in the rewind cards.

Desired behavior

Add an option in the dashboard settings to define a custom name or use the Plex server name to replace all instances of 'Plex' in the rewind cards.

Additional context

No response