Feature: Add support for an all-in-one script - failure modes InsufficientInstanceCapacity

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as a user, i just want to run one script .. puhlease !!

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failure scenarios - no spot capacity available part way through process

e.g. all instances terminated, ec2 conversion fails with temporary resource issues:

botocore.exceptions.ClientError: An error occurred (InsufficientInstanceCapacity) when calling the RunInstances operation (reached max retries: 5): We currently do not have sufficient m5a.2xlarge capacity in the Availability Zone you requested (ap-southeast-2a). Our system will be working on provisioning additional capacity. You can currently get m5a.2xlarge capacity by not specifying an Availability Zone in your request or choosing ap-southeast-2b, ap-southeast-2c.

An error occurred (InsufficientInstanceCapacity) when calling the StartInstances operation (reached max retries: 2): You can't start the Spot Instance 'i-003bc5e90fbd29150' because there is no available Spot capacity.

to make things fully re-runnable, we would need to search for "terminated" instance(s) and retry the conversion command, or cache it in a .dotfile perhaps and retry n#times until successful.

or (at the least) provide some manual HELP/instructions when this occurs.