loginIn with username option on auth

[ykethan]

Environment information

System:
  OS: macOS 14.3.1
  CPU: (8) arm64 Apple M1
  Memory: 206.27 MB / 16.00 GB
  Shell: /opt/homebrew/bin/fish
Binaries:
  Node: 18.19.0 - ~/.local/share/nvm/v18.19.0/bin/node
  Yarn: 3.6.4 - ~/.local/share/nvm/v18.19.0/bin/yarn
  npm: 10.2.3 - ~/.local/share/nvm/v18.19.0/bin/npm
  pnpm: 8.15.4 - ~/Library/pnpm/pnpm
NPM Packages:
  @aws-amplify/backend: 0.13.0-beta.5
  @aws-amplify/backend-cli: 0.12.0-beta.5
  aws-amplify: 6.0.19
  aws-cdk: 2.132.0
  aws-cdk-lib: 2.132.0
  typescript: 5.4.2
AWS environment variables:
  AWS_STS_REGIONAL_ENDPOINTS = regional
  AWS_NODEJS_CONNECTION_REUSE_ENABLED = 1
  AWS_SDK_LOAD_CONFIG = 1
No CDK environment variables

Description

Amplify Gen 2 currently only supports email and phone number but does not username which cognito allows as an option when creating a new userpool