Add Azure Bicep recipe for postgreSqlDatabases

[willtsai]

Motivation

The Radius.Data/postgreSqlDatabases resource type only has recipes for Kubernetes-hosted PostgreSQL instances. This PR adds an Azure recipe that provisions Azure Database for PostgreSQL Flexible Server, giving platform engineers a cloud-managed option for PostgreSQL databases.

Approach

The new Bicep recipe at Data/postgreSqlDatabases/recipes/azure/bicep/azure-postgresql.bicep provisions:

• An Azure Database for PostgreSQL Flexible Server with configurable version (default 16) and storage
• A database on that server with UTF-8 charset and en_US.utf8 collation
• A firewall rule allowing Azure services access (dev/test default)

Key design decisions:

• Credentials from connected secrets -- follows the ACI recipe pattern where the recipe reads USERNAME and PASSWORD from context.resource.connections using the secretName property. This works with the Radius.Security/secrets resource backed by Azure Key Vault, so no @secure() recipe parameters are needed.
• Size-to-SKU mapping -- maps the size property (S/M/L) to Azure SKU tiers: S -> Burstable B1ms, M -> GeneralPurpose D2s_v3, L -> MemoryOptimized E2ds_v4
• Globally unique naming -- uses uniqueString(context.resource.id) to generate collision-free server names across environments
• Safe navigation -- uses .? throughout for optional context paths per Bicep best practices, and - instead of / in Azure tag names

Notes

• The firewall rule (0.0.0.0) allows all Azure services -- production recipes should use private endpoints or scoped rules
• The recipe outputs host, port, and database in result.values, matching the resource type's read-only properties

[willtsai]

@copilot - take a look at this PR where an initSql property was added and implemented in the Kubernetes postgreSQL recipe. Please implement the same functionality in the Azure PostreSQL recipe here.

[Copilot]

@copilot - take a look at this PR where an initSql property was added and implemented in the Kubernetes postgreSQL recipe. Please implement the same functionality in the Azure PostreSQ...

Added initSql support to the Azure recipe in c7fdf6a. Since Azure Database for PostgreSQL Flexible Server has no /docker-entrypoint-initdb.d/ equivalent, the recipe now provisions a Microsoft.Resources/deploymentScripts (Azure CLI container) when initSql is non-empty. It installs postgresql-client and runs the SQL via psql -v ON_ERROR_STOP=1 against the newly created database, using the same admin credentials read from the connected secret. The SQL is passed as a secureValue so it doesn't leak into deployment logs, and the script depends on the firewall rule so it can reach the server.