Add tutorial for building a full-stack application with Smithy

[haydenbaker]

Background

• This is a draft, there are still some changes to be made and edits (also updates based on updates to the example linked below)
• This pairs with Add a basic web application tutorial using smithy smithy-examples#101
• Adds a new category, tutorials, to the site
• Adds a new tutorial that explains how to build an e2e application using smithy (client, server, web-app)

Testing

• needs add doc autobuild and dev target #2361
• make dev, check rendered page
• follow tutorial

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