Update all entities network hash after a server package has been installed - sboxgame/issues#3635
Adding a new server package would correctly change the DynamicAssemblyHash
on both server and client, however all current entities would still have
the old DynamicAssemblyHash.
This would mean the clients would receive no [Net] updates for this entity.
So to fix this we explicitly reset all entities network hash with
Entity.UpdateAllNetworkHash() on OnServerPackageInstalled.
Reinitializing the network tables would've also worked but would be
wasteful since we know all our exisiting entities have not been changed
unlike if the DynamicAssemblyHash were changed from hotload