feat(packets): add many new packets

fix(packets): make UpgradeRare packet deserialize correctly

feat(packets): add PerparedLevel to PacketStringEnumerator's levels to allow multiple prepared levels for nested packets

feat(samples): update file client QoL

chore: make Directory.Build.props correct case

feat(samples): add file client logging of failed parsing or missing packets

chore(packets): add documentation for ski packet

fix(packets): make generator work with packets that have 0 members

chore: make Core internals visible to tests

Merge pull request #34 from Rutherther/tests

Add core tests

fix(tests): add needed using

feat(tests): use merged HandlePacketAsync method

fix(tests): expect FakeError instead of GenericError

fix(tests): add default packet serializers

feat(tests): add tests for command processor, walk command handler, stateful injector

fix(packets): make UpgradeRareSubPacket converter work with "0"

feat(tests): add player test with 0 UpgradeRareSubPacket

chore: update tests

fix(packets): make bs packet effect id nullable

fix: correct usings