Include non-Route 53 DNS configuration option in AWS CloudFormation template

[ag-adampike]

Our current CloudFormation template automates DNS record management using Amazon Route 53 for the records that are required:

• to valid ownership of the domain used with AWS Certificate Manager (ACM) to request a TLS certificate presented by the load balancer
• to point from the domain name in this certificate to the load balancer IP address

In this PR, we will enhance our CloudFormation template to enable customers to deploy 1Password SCIM bridge by creating these records in another DNS provider.

The initial commit on this branch modifies the existing template to exclude the Route 53 resources, refactor references to it and its attributes, and enable manual rather than automated record creation for ACM validation. It currently works as expected for this use case.

Criteria for graduating from draft:

• ensure refactored references work as expected when re-enabling Route 53 resources for the "general" use case
• enable a means to optionally disable creation of Route 53 resources and automatically provide correct attributes for the ACM Certificate resource (e.g. if Route 53 Zone is not selected)
• add any necessary validation
• include a conditional output of the DNS record that must be created to point to the load balancer
• test using CLI deployment
• update instructions in README accordingly