Add shorter, more compact docs for AWS CLI, Docker, AWS SAM CLI setup than what's already out there

**Is your feature request related to a problem? Please describe.**

Today, before users can use the AWS Toolkit to do AWS serverless development or to run/debug AWS Lambda functions locally, users are currently sent off to the AWS CLI and AWS SAM CLI setup documentation that's spread out over the AWS website--as well as sent off to the Docker setup documentation elsewhere--to set up these prerequisites manually.

**Describe the solution you'd like**

Add documentation to the _AWS Toolkit for VS Code User Guide_ that contains summarized, compact sets of commands that customers can run to manually install the AWS CLI, Docker, and the AWS SAM CLI as quick as possible.

**Describe alternatives you've considered**

Ideally, there should be a way to do this a lot faster than a bunch of manual commands. But for now, hopefully this would be a better documentation experience than what it is currently.

Start with the AWS Toolkit for VS Code User Guide and compare its current prerequisite links with the AWS CLI, Docker, and AWS SAM CLI setup documentation referenced in the issue. Done means the guide contains compact, runnable installation command sets that reduce the need to consult those separate sources.

Written by the indexing model from the issue text.