Add S3 bucket and DynamoDB table modulesAdd Terraform modules for S3 bucket and DynamoDB table

[Vikas-Abhimanyu]

This PR adds two new modules under modules/:

• s3_bucket: Creates an S3 bucket with optional versioning and tagging.
• dynamodb_table: Creates a DynamoDB table with configurable keys, billing mode, and capacity.

Each module includes:

• main.tf for resource definitions
• vars.tf for input variables
• outputs.tf for outputs

These modules follow the same structure as the existing EC2 module and provide reusable building blocks for AWS infrastructure.