Set User-Agent string for requests

[twodayslate]

As requested by @pushcx

#19 (comment)

Awaiting official guidance on what the string should be

[twodayslate]

@pushcx wants $APP_NAME/$VERSION ($ARCH; $OS; +https://contact.link/for/the/app)

[twodayslate]

I'm implementing this as I convert my network calls to async. See #29

As requested this is what I was returning on the simulator:

(lldb) po ua
"claw/1.2.0 (hppa; iOS 15.5; +https://zac.gorak.us/ios)"

I don't see much value in the architecture so I'm changing it to the device model.

This is what you will then see:

(lldb) po ua
"claw/1.2.0 (iPhone10,4; iOS 15.5; +https://zac.gorak.us/ios)"

You can lookup the models here: https://www.theiphonewiki.com/wiki/Models