feat: add init prompts for Gen2

[0618]

Description of changes

This PR is to add some prompts before a user init a new Gen1 project.

• If user decide to not continue with Gen1, exit the process.

• If user decide to continue with Gen1, ask for the reason

• Add the reason to project-config.json

• Add to stack metadata

• Only show the prompts in a new project.
• The change doesn't affect headless mode.

Issue #, if available

Description of how you validated changes

• tested all the scenarios above on my local machine.

Checklist

• [x] PR description included
• [x] yarn test passes
• [ ] Tests are changed or added
• [ ] Relevant documentation is changed or added (and PR referenced)
• [ ] New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies
• [ ] Pull request labels are added

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[awsluja]

can you run e2e?