types: map::to_string() - non-empty implementation
types: map::to_string() - non-empty implementation

Print a map in the form of [(]{ key0 : value0 }[, { keyN : valueN }]*[)]
The map is printed inside () brackets if it's frozen.

Signed-off-by: Vlad Zolotarov <976c0f8d0852ed6439ad273880b400a75a7c41d0@cloudius-systems.com>

scylladb/scylla,avikivity/scylla,raphaelsc/scylla,kjniemi/scylla,duarten/scylla,kjniemi/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla,kjniemi/scylla,raphaelsc/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,duarten/scylla,raphaelsc/scylla