[tarantool-c] Add missing C methods and variables

**Product:** C connector
**Audience/target:** devs
**Root document:** https://tarantool.github.io/tarantool-c/

# Details

tnt_get_spaceno
tnt_object_add_int
tnt_object_add_str
tnt_object_add_float
tnt_object_format
tnt_reply.error
tnt_auth_raw
tnt_auth