Docs for SQLServer managed identity config

[danielgerlag]

This pull request updates the SQL Server source configuration documentation to add support for authentication using Microsoft Entra Workload Identity (Managed Identity) in Azure environments. The documentation now includes details on configuring the source for managed identity authentication, step-by-step AKS setup instructions, and guidance for granting SQL permissions.

Authentication and Identity Configuration:

• Added documentation for the authentication property in the SQL Server source configuration, explaining how to use ActiveDirectoryManagedIdentity for managed identities and when to omit it for username/password authentication.
• Introduced a new identity section under the source spec, describing how to configure Microsoft Entra Workload Identity, including the required properties (kind, clientId) and a YAML example.

Azure AKS and SQL Setup Instructions:

• Provided detailed AKS setup steps for enabling Workload Identity, creating managed identities, assigning roles, and creating federated credentials for the source.
• Added SQL commands for creating an external user for the managed identity and granting it read permissions on the database.

Reference Links:

• Included related links to official Microsoft documentation for managed identities, workload identities, and AKS setup for further reading.

[Copilot]

Pull Request Overview

This PR adds comprehensive documentation for SQL Server source configuration to support Microsoft Entra Workload Identity (Managed Identity) authentication in Azure environments, eliminating the need to store sensitive credentials.

• Added authentication property documentation for using ActiveDirectoryManagedIdentity with managed identities
• Introduced new identity configuration section with Microsoft Entra Workload ID support
• Provided detailed AKS setup instructions and SQL permission configuration steps

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