Simplify EC2 startup workflow

[sbailey]

Thanks for documenting all the steps to run an EC2 + Docker instance in the top level README.md .

Is there a version of this workflow where we could pre-configure all of the settings and pre-install everything to minimize the number of steps the user has to take? I still want the end-user to pay and not scale up an instance that we would have to pay for, but is there any way that we can dramatically simplify this, along the lines of "login to your AWS account and click this to launch a DESI jupyter server that will be charged to your account"? Even if they have to configure the security policy stuff by hand, it would even be helpful if the final "run this in the container" steps were wrapped in a one-liner script that users could download + run and it would print out the URL of the jupyter server at the end.

[xingyzt]

Might be possible with EC2 image builder. Will look into it later this week.