Add InitSQL Support for AWS RDS Postgres Instances

[universe-ops]

Implemented InitSQL support for AWS RDS Postgres instances to enable custom SQL execution during database initialization.

Changes Made

• Added InitSQL field to PostgresConfig in pkg/clouds/aws/rds_postgres.go

  • Optional field for custom SQL commands during database setup
  • Supports multi-line SQL for complex initialization

• Enhanced compute processor in pkg/clouds/pulumi/aws/compute_proc.go

  • Modified to pass InitSQL configuration to the initialization script
  • Leverages existing PSQL_DB_INIT_SH script infrastructure

Usage Example

resources:
  postgres-db:
    type: aws-rds-postgres
    config:
      name: "my-postgres"
      instanceClass: "db.t3.micro"
      engineVersion: "15.4"
      username: "dbuser"
      password: "${secret:postgres-password}"
      initSQL: |
        CREATE EXTENSION IF NOT EXISTS vector;
        CREATE EXTENSION IF NOT EXISTS pg_stat_statements;
        ALTER SYSTEM SET shared_preload_libraries = 'pg_stat_statements';