Add welcome view to the user at the beginning

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After the user run the command-line, show the welcome message to the user. including:

• Unicon poster
• Simple description of AWS SQS service and official URL link.
• Help message about how to use this tutorial.

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Amazon Simple Queue Service

Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications.

SQS offers two types of message queues:

• Standard queues:

offer maximum throughput, best-effort ordering, and at-least-once delivery.

• SQS FIFO queues:

are designed to guarantee that messages are processed exactly once, in the exact order that they are sent.