variant of expiry check helpers that exposes remaining time?

[robx]

I'd like to check not just whether a token is expired, but whether it's close to expiry. To that extent, an API like the following would be great (which would easily allow implementing the current specialized functions):

getTokenExpirationMillis : String -> Result JwtError Int
getTokenExpirationMillis = ...

getTokenTimeToExpirationMillis : String -> Task JwtError Int
getTokenTimeToExpirationMillis = ...

What do you think? I'd be happy to provide a PR if you think this is a good idea.

[simonh1000]

I'd welcome a PR for getTokenExpirationMillis but I think the latter should be left to users