Flutter melos config and scripts

Melos config.yaml

name: melos_demo_app

packages:
  - packages/core/**
  - packages/events/**
  - '*'

scripts:
  test:selective_unit_test:
    run: melos exec --dir-exists="test" --fail-fast -- flutter test --no-pub --coverage
    description: Run Flutter tests for a specific package in this project.
    select-package:
      flutter: true
      dir-exists: test
  test:
    run: melos run test:selective_unit_test --no-select
    description: Run all Flutter tests in this project.
  analyze:
    run: melos exec -- flutter analyze .
    description: Run `dart analyze` in all packages.