Consolidate domain configs

[lorenyu]

Ticket

n/a

Changes

• Consolidate hosted_zone, domain_name, and enable_https to a domain_config object separate from the service_config object
• Remove unneeded variable domain_name from identity_provider/resources

Context for reviewers

While working on another PR I realized the domain configs are intermingled with service configs. This PR cleans that up. Also removed a variable that we don't need since we can just use the configuration set that's associated with the domain identity.

Testing

Running make infra-update-app-service APP_NAME=app ENVIRONMENT=dev shows no changes

Also tested notifications to make sure it still works

Preview environment

♻️ Environment destroyed ♻️

[lorenyu]

Done in navapbc/template-infra#839