Better error messages when failing to parse pubspec

[sigurdm]

# pubspec.yaml:
name: blah
environment:
  sdk: ^3.6.0
dependencies:
  build:
    git: https://github.com/dart-lang/build

> dart pub get
Resolving dependencies... 
(53.5s)
Error on line 1, column 7: "name" field doesn't match expected name "build".
  ╷
1 │ name: build_workspace     # Can be anything
  │       ^^^^^^^^^^^^^^^
  ╵                                     

Would be nice to show the path of inclusion to parsing the dependency.