* HipcGenerator: skip do-nothing call to MemoryMarshal.Cast<byte, byte>() in generated code
* HipcGenerator: fix method name typos
* HipcGenerator: make generated methods use stackalloc for `isBufferMapAlias` bool array
* HipcGenerator: make generated GetCommandHandlers() method return a FrozenDictionary<int, CommandHandler>
* HipcGenerator: return `FrozenDictionary<,>.Empty` when there are no command implementations, otherwise create `FrozenDictionary` from a `IEnumerable<KeyValuePair<,>>`` instead of a `Dictionary<,>``