Returns default anonymized value based on field type

@default_integer 0
@default_float 0.0
@default_string "redacted"
@default_map %{}
@default_decimal Decimal.new("0.0")
@default_date ~D[1970-01-01]
@default_datetime ~U[1970-01-01 00:00:00Z]
@default_datetime_usec ~U[1970-01-01 00:00:00.000000Z]
@default_naive_datetime ~N[1970-01-01 00:00:00]
@default_naive_datetime_usec ~N[1970-01-01 00:00:00.000000]
@default_time ~T[00:00:00]
@default_time_usec ~T[00:00:00.000000]