Implement Temporal.PlainMonthDay.prototype.toLocaleString

[jedel1043]

Spec: https://tc39.es/proposal-temporal/#sec-temporal.plainmonthday.tolocalestring

[alienx5499]

Hi @jedel1043,

I’d like to work on this.

I’m currently implementing Temporal.PlainYearMonth.prototype.toLocaleString in #5098 using the shared format_date_time_locale pipeline introduced in #5080.

Once that lands, I plan to implement Temporal.PlainMonthDay.prototype.toLocaleString using the same approach.

If that sounds good, please feel free to assign this issue to me.

Thanks!