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 a formatter for
row_level_diff_detect_algorithm. but its operator<<() is preserved,
as we are still using our homebrew the generic formatter for
std::vector, and this formatter is still using operator<< for formatting
the elements in the vector.
Refs #13245
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#16248
28906725df