Use MySQL Flexible Server instead of Single Server w/ is EOL 2024

[phillipedwards]

This PR makes the following changes:

• 01-infrastructure now uses azure-nativev2 (currently beta).
• 01-infrastructure creates MySQL Flexible Server rather than Single Server; SS is EOL 9/24.
• 01-infrastructure creates two subnets; one for AKS and one delegated subnet for MySQL
• 01-infrastructure creates a Private DNS Zone and records to allow MySQL DB to be completely private; only AKS subnet is allowed direct communication w/ DB.
• 02-kubernetes make AzureDnsCertManagement the default, but can be disabled