Api rewrite

[c6fc]

Merge api_rewrite into dev. This includes multiple changes:

• Terraform version bump to 0.15
• Improvements in lambda function readability and error handling; async/await with try-catch blocks on each segment:
• • rewrite of API gateway generator and break-out of proxy_api_handler
• • rewrite of spot_monitor
• Dockerfile bumped to AWSCLIv2, with quality-of-life changes to make existing deployments easier to manage
• • Docker now contains all the prereqs for self-hosted deployments, so advanced deployments can be entirely managed via Docker.
• Multiple redundant settings were removed, such as 'useSAML', 'useCustomDns', and 'dnsNames'. These are now assumed based on whether a SAML Metadata file or Route53 zone ID is provided, and the deployment URL is now derived from the Route53 Zone.
• SAML login is now supported without custom DNS, and works correctly with events and settings.