msgpack::map_view can be used to iterate, pair-wise, over a range of
msgpack::token. It will immediately return if the first token is not a
map, and will skip over nested map/arrays.
Note for the future: It will be handy to be able to get the subspan
corresponding to the nested map/array. Will think about how to solve
that later.
Begin incorporating map_view into the server.
Add formatters for std::byte, dynamic theme for bool, and spans thereof.
Maybe switch to range?
This essentially completes the token_reader. In the future, we will
probably want something that lets us allocate maps/arrays more
seamlessly, but we can start working on client-server architecture with
this reader.