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
* mutation_partition_v2::printer
* frozen_mutation::printer
* mutation
their operator<<:s are dropped.
Refs #13245Closesscylladb/scylladb#17769
* github.com:scylladb/scylladb:
mutation: add fmt::formatter for mutation
mutation: add fmt::formatter for frozen_mutation::printer
mutation: add fmt::formatter for mutation_partition_v2::printer