Save install-subnet-chain commands in a file

When using `avalancheup-aws apply` the end result is a list of endpoints and commands that can be run, for things like installing a new chain on the network. These commands are very helpful, but since they are only emitted to stdout, they can get lost in the terminal. I think writing the output of `apply` to stdout and a file (with the same `aops-` convention as the spec yaml file) could be helpful as a resource for users to retain access to all the auto-generated commands across terminals.

Start at the `avalancheup-aws apply` entry point and trace where its endpoints and generated install-subnet-chain commands are emitted to stdout. Done means the apply output remains on stdout and is also saved to a file using the same `aops-` convention as the spec YAML file, so users can retrieve it across terminals.

Written by the indexing model from the issue text.