feat: add fn_login_steamcmd_nopass function
This commit adds the `fn_login_steamcmd_nopass` function to the core_steamcmd.sh module. This function is called in the `fn_update_steamcmd_remotebuild` function and handles logging into SteamCMD without a password. The purpose of this change is to improve the login process for SteamCMD when updating remote builds.