## Description
- Remove duplicate packet definitions by using `Cow`.
- Rename packets to match yarn mappings.
- Remove some top-level re-exports.
- Move every packet into its own module for consistency.
- Move packet-specific types from the `types` module into the
appropriate packet module.
- Remove internal use of `EncodePacket`/`DecodePacket` derives and move
packet identification to `packet_group`. This can be done because there
are no duplicate packets anymore.
- Simplify some events.
In a future PR I plan to clean things up further by properly bounding
packet data (to prevent DoS exploits) and fixing any remaining
inconsistencies with the game's packet definitions.
## Test Plan
Behavior of `valence_protocol` should be the same.
Steps:
1. Use the packet inspector against the vanilla server to ensure packet
behavior has not changed.
2. Run the examples.
3. Run `valence_stresser`.
