Set up repo

[estherkim]

• update README
• set up eslint
  • Add initial tsconfig and eslint to work with ts, prettier #10
• set up prettier
  • Add initial CI with prettier check, package.json #8
• set up CI framework
  • Add initial CI with prettier check, package.json #8
• set up tsconfig
  • Add initial tsconfig and eslint to work with ts, prettier #10
• set up test framework
• create branch protection rules
• create directory structure
• determine compilation strategy
  • ✨ 🏗 Create Bento build-system #12
• determine publishing strategy
• determine migration strategy

[rileyajones]

ampproject/amphtml#37597