proposal: introduce a better architecture to handle multiversion

[smartcmd]

We need a better architecture to handle multiversion stuff, and since now most of the network operations are go through Player/AllayPlayer, we can just use a inherit chain as the following:

• AllayPlayer: the base class, which is used for the latest version client.
• AllayPlayer_v860 -> AllayPlayer: used for 1.21.120 client.
• ...
• AllayPlayer_v766_NetEase ->AllayPlayer_v766

Or instead of modifying AllayPlayer, we can introduce a new MultiversionHelper class just like the BedrockCodecHelper in the protocol library.

There should also be changes to the current PacketProcessor system, to introduce different packet processor for different protocol version.