The most important enhancement is to remove soon-to-be deprecated
LaunchConfiguration pieces and replace with LaunchTemplates

- Parameterise several values previously hardcoded in the template
  - AMI ID
  - Backend instance type
  - Load balancer TLS Policy
  - DNS Zone ID
- Rename some parameters to reflect their meaning better
- Improve parameter types to make validation easier
- Add secrets to AWS Secrets Manager and add their ARN tail as params
  - DB credentials
  - SMTP credentials
  - OAuth2 credentials
  - TM Secret
- Remove parameters replaced by Secrets Manager entries
- Simplify condition names
- Remove Launch Configuration and replace with Launch Templates
- Move package install from user-data to Metadata section

- [MISC] Move default backend instance type to t3.small
- [MISC] Add us-east-1e to AZ list
- [ENHANCE] Upgrade PostgreSQL version to 13.x
- [ENHANCE] Create a parameter group and assign to RDS instance based on
  parameter group family
- [MISC] Move default datase instance type to db.t4g.xlarge
- [MISC] Rename Parameters to make them more meaningful
- [ENHANCE] Fix names of resources - instead of using cf.stackName, use a simpler
  one.
- [FIX] Switch to LaunchTemplateId from LaunchTemplateName
- [ENHANCE] Parameterize disk size, snapshot retention period, etc.,
  based on IsProduction condition
- [SECURITY] Add a more restricted S3 Bucket Policy for frontend bucket
- [ENHANCE] Add an Origin Access Control policy to CloudFront
- [ENHANCE] Add a custom cache policy to CloudFront
- [ENHANCE] Better defaults for CloudFront distribution
  - Enable http2
  - Enable IPV6
  - Add Route53 Recordset Group instead of a standalone RecordSet
    to add both A records and AAA records
  - Upgraded TLS Protocol Version option

The issue:
If CloudFront needs to connect to S3 - We add an S3Origin. However, if
the S3 bucket is configured as a website, it needs to be considered a
custom origin. And custom origins can't have OriginAccessControl.

The Solution:
Removed Origin Access Control.

- User data needed python to be installed in order to get cfn-init
  to work. Fixed that.
- Cloud init scripts are run as root by default. so removed sudo