rest/models: print out timestamps in more appealing format

[kevinburke]

Previously if you printed a models.Millis with %#v you would get something that looked like this:

models.Millis{wall:0x0, ext:63816264000, loc:(*time.Location)(0x105256980)

Which doesn't tell you at a glance what time it represents. This change makes it print out a prettier looking string that tells you what time it represents.

Millis(time.Date(2023, time.April, 3, 21, 0, 0, 0, time.Local)

I previously merged the same change to the Go standard library.

[justinpolygon]

Hey @kevinburke, thanks for submitting this. I wanted to learn about your use-case for this a little. We have been exploring this idea for our client libraries and wanted to add helper functions that turn unix time into something human readable (1692115582246 -> 2023-08-15 12:06:22.246135-04:00). I just wanted to learn about your use-case for why you'd need it in this format time.Date(2023, time.April, 3, 21, 0, 0, 0, time.Local) vs something like 2023-08-15 12:06:22.246135-04:00. I'm assuming it's so that you can just copy/paste into areas of your code but wanted to check.

[kevinburke]

apologies - I can't even remember the context where I encountered this library, sorry

[justinpolygon]

You're good @kevinburke. Was just looking at something related and was going to merge this. Also, it looks like we can use something like this for Nanos as well. Cheers. Sorry for the massive delay here.

[justinpolygon]

Going to refactor a bit and submit my own PR. I'll close this out for now.