Remove unused flag images from the admin resource

[DateFTP]

The country flags under [admin]/admin/client/images/flags/ are no longer needed.

The admin resource has been loading player flags from the separate ip2c resource for a while now (admin_main.lua references :ip2c/client/images/flags/), so these local copies are never used. Since the ip2c resource ships its own flag set, keeping duplicates here just adds ~200 files to the repository for nothing.

This removes the whole flags folder and nothing else. No code or config references these files, and meta.xml does not list them either.

Confirmed nothing else in the resource points at client/images/flags, so this should be a safe cleanup.

[DateFTP]

Confirmation in the request to the ip2c folder for obtaining flag images.
Path: [admin]\admin\client\gui\admin_main.lua - 1449