0.8a3

[Chenglong-MS]

This pull request adds delegated Microsoft OAuth sign-in support for Kusto (Azure Data Explorer) connectors and introduces local Azure CLI authentication endpoints, while also making several related improvements. The main changes are the introduction of a new OAuth gateway, new endpoints for Azure CLI login/status, and enhancements to how authentication parameters are handled and surfaced to the frontend.

Kusto OAuth delegated sign-in:

• Added a new blueprint kusto_oauth_bp in kusto_oauth_gateway.py to support Microsoft delegated OAuth (Authorization Code + PKCE) for Kusto connectors, including all supporting logic for secure state, PKCE, and token exchange.
• Registered the new Kusto OAuth blueprint in the app initialization, making the endpoints available.
• Set new environment variables in local_server.sh to configure the Kusto OAuth flow for local development.

Local Azure CLI authentication endpoints:

• Added /api/local/azure-status and /api/local/azure-login endpoints that allow the frontend to check Azure CLI login status and trigger interactive login, for connectors supporting Microsoft Entra ID authentication.

Connector login flow improvements:

• Enhanced _resolve_delegated_login to include a params field, allowing the frontend to receive additional parameters needed for delegated login.
• When connecting with delegated login, now records the token expiry time (token_expires_at) for better session management.

Other:

• Registered the Databricks data loader in the loader registry.