The purpose of ClientToken is to ensure request idempotency in case the request needs to be retried. This means the value must be unique for all unique RunInstances API calls.

When building a template that references the same source multiple times (or multiple different sources), many calls to RunInstances are made. However, the same auto-generated instance name was used as "ClientToken".

This changes ClientToken to be unique regardless of whether the user has supplied a unique "instance_name" for each source/build.

Fixes hashicorp#6

Fix multisource clienttoken

fix: Support SkipCreateImage field to skip creating an image