feat: update managed identity configurations and enhance web security

[Akhileswara-Microsoft]

Purpose

This pull request introduces several improvements to the Azure infrastructure Bicep modules, with a focus on enhancing security defaults and managed identity configurations. The most significant changes include enforcing secure defaults for web applications, setting system-assigned managed identities by default, and improving identity assignment for Event Grid subscriptions.

Security and Configuration Enhancements:

• Enforced FTPS-only, minimum TLS version 1.3, and HTTPS-only settings by default for web app configurations in web-sites.config.bicep to improve security posture.

Managed Identity Improvements:

• Changed the managedIdentities parameter in host/appservice.bicep to default to a system-assigned managed identity, simplifying identity management for app services.
• Added a SystemAssigned identity to the Microsoft.Web/sites resource in azure.bicep, ensuring all web apps have a managed identity by default.

Event Grid Enhancements:

• Updated the Event Grid System Topic module in eventgrid.bicep to support delivery with a user-assigned identity, allowing for more flexible and secure resource access in event subscriptions.

Does this introduce a breaking change?

• Yes
• No