Feature Request: Add grace period to SEP-10 challenge parsing function

[JakeUrban]

What problem does your feature solve?

Its possible for the SEP-10 challenge's minTime constraint to be "in the future" for the client application parsing the challenge due to clock drift.

What would you like to see?

We've implemented a grace period for the min time constraint in the Go SDK, and both the min and max time in the JS SDK. I'd like us to do the same here.

What alternatives are there?

N/A

[salimwyre]

👍 When using the SDK as a client and the test anchor as a server we hit that case "minTime in the future" about 5% of the time