tuple: use global msgpack serializer in Lua tuple

Tuple is a C library exposed to Lua. In Lua to translate Lua
objects into tuples and back luaL_serializer structure is used.

In Tarantool we have several global serializers, one of which is
for msgpack. Tuples store data in msgpack, and in theory should
have used that global msgpack serializer. But in fact the tuple
module had its own private serializer because of tuples encoding
specifics such as never encode sparse arrays as maps.

This patch makes tuple Lua module use global msgpack serializer
always. But how does tuple handle sparse arrays now? In fact,
the tuple module still has its own serializer, but it is updated
each time when the msgpack serializer is changed.

Part of #4434

(cherry picked from commit 676369b1)