Enhanced server list file management

[SpoilerRules]

Improve the accessibility and usability of server list file selection by:

1. Allowing users to quickly select a server list file from recent picks directly within the server file list add dialog
2. Supporting multiple server list files through a unified list for better organization, ideally presented as a split button: the primary action adds a new server list file, while the dropdown displays saved server list files in an organized manner, along with an option to manage the unified list (e.g., delete entries). The layout would resemble: [ADD] [Dropdown Menu] [MANAGE]
3. Ensuring that selecting and switching between server list files is intuitive and efficient by presenting the actions (as described in point 2) directly on the multiplayer screen, so no extra clicks are required