before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.
in this change, we define formatters for db::schema_tables::table_kind,
and its operator<<() is still used by the homebrew generic formatter
for std::map<>, so it is preserved.
Refs #13245
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#16972
0fbfc96619