feat:add template validation

[Tejasri-Microsoft]

This pull request restructures and improves the CI/CD workflows for Azure template validation and deployment. It separates template validation and deployment into distinct workflows, modernizes the deployment process, and enhances security and maintainability.

Workflow separation and improvements:

• Added a new workflow .github/workflows/azd-template-validation.yml dedicated to scheduled and manual Azure template validation using the microsoft/template-validation-action, with improved permissions and environment variable management.
• Refactored .github/workflows/azure-dev.yml to focus solely on deployment, renaming it to "Azure Dev Deploy" and removing template validation steps.

Deployment process enhancements:

• Updated deployment workflow to use Azure/setup-azd@v2 for installing azd and switched authentication to federated credentials via azd auth login, improving security and aligning with best practices.
• Added environment variable injection for deployment-related Azure resources, supporting more flexible and configurable deployments.
• Streamlined deployment logic by checking for existing environments, setting configuration values, and running azd up for provisioning and deployment.## Purpose

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Does this introduce a breaking change?

• Yes
• No

Golden Path Validation

• I have tested the primary workflows (the "golden path") to ensure they function correctly without errors.

Deployment Validation

• I have validated the deployment process successfully and all services are running as expected with this change.

What to Check

Verify that the following are valid

• ...

Other Information