Add Colors Support for Sockets Filter

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• "Sockets" now supports everything "SocketGroup" does, except it applies to all sockets on the item and doesn't care about links. E.g. "5GGG" will show items with exactly 5 total sockets, if at least three of them are green.
• "Sockets" previously only supported a number of sockets, but these changes are fully backwards-compatible. So "Sockets 4" will still match any item with exactly 4 sockets, same as before. Similarly "Sockets >= 5" etc.