package:build v3.0.0

• Removed unused deps: meta, pool.
• Breaking: use the new element2 APIs in analyzer. Builders that do
  resolution need to switch to the new API, see
  https://github.com/dart-lang/sdk/blob/main/pkg/analyzer/doc/element_model_migration_guide.md.
  For questions please use https://github.com/dart-lang/build/discussions.