Add server-side GM visibility control script

[Yehonal]

TLDR: .Introduce a player script to manage server-side visibility for game masters, ensuring players with gm visible command can properly use it

This pull request introduces a new player script to enhance server-side visibility handling for Game Masters (GMs). The main change is the addition of logic that automatically upgrades a player's account type to SEC_GAMEMASTER when certain conditions are met, ensuring proper GM visibility permissions.

Enhancements to GM visibility logic

• Added a new class mod_gm_commands_playerscript in src/GmCommands.cpp that overrides OnPlayerSetServerSideVisibility to set a player's account type to SEC_GAMEMASTER when they should be visible as a GM and have the appropriate permissions.
• Registered the new player script in the AddGmCommandScripts function to ensure it is loaded with other GM command scripts.
• Included the PlayerScript.h header in src/GmCommands.cpp to support the new player script functionality