proposal: time: add MarshalText/UnmarshalText to time.Duration

[islishude]

should we reconsider the proposal #16039 ?

Adding these methods to time.Duration would make it easier to write and read JSON data containing time.Duration objects.

[ianlancetaylor]

Per #10275, I don't think we are going to make this change.

[seankhliao]

There's no new information for us to reconsider, and the rules we've decided on say we can't.