Implement `CBasePlayerItem::` hooks

[wopox1337]

• CBasePlayerItem::Materialize()
  for handling items disappearing after they respawn and touch fix

• CBasePlayerItem::CheckRespawn()
  for use removed Respawn() https://github.com/tmp64/BugfixedHL-Rebased/blob/7af2b2a5994a9f77051b06425a38687a09c80f61/src/game/server/weapons.cpp#L531

[lozatto]

#997