Provide a Kotlin MPP UUID generator

[kggilmer]

This is required for the idempotentTokenGenerator task. Kotlin does not have any platform agnostic support for UUID generation.

The go SDK references: https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_.28random.29

From smithy-go/rand/uuid.go

Verify fixes: awslabs/aws-sdk-kotlin#69

internal id: 175157019

[aajtodd]

https://github.com/benasher44/uuid looks like a good candidate that we could leverage to bootstrap things and re-evalute the dependency later.

There is some discussion in KT-31880 about this library being a community driven proving grounds.

I've looked it over and the library is using:

• java.util.UUID on JVM (uses SecureRandom)
• delegates to /dev/urandom on native
• BCryptGenRandom on windows
• kotlin.random.Random on JS
  • note this should probably should be Crypto.getRandomValues() for browsers (but likely wouldn't work on node which is probably why they used the builtin RNG)

Alternatively we can go platform by platform and implement it ourselves. There is no builtin CSPRNG for KMP out of the box (KEEP 185 proposes adding one). If we are only going to use the uuid strictly for idempotency tokens then it's probably fine to use a non-cryptographically secure RNG but I'd be hesitant to put a general purpose uuid type/generator into our runtime lib without further considerations.