Support pub workspaces

[dcharkes]

resolution: workspace

dev_dependencies:
  repo_lint_rules:
    path: ../repo_lint_rules/

succeeds

resolution: workspace

dev_dependencies:
  repo_lint_rules: 0.1.0-wip

fails with the following error

+dart analyze --fatal-infos pkgs/code_assets pkgs/data_assets pkgs/hooks pkgs/hooks_runner pkgs/json_syntax_generator pkgs/native_toolchain_c pkgs/repo_lint_rules
Analyzing code_assets, data_assets, hooks, hooks_runner, json_syntax_generator, native_toolchain_c, repo_lint_rules...

An error occurred while executing an analyzer plugin: Exception: Failed to run "pub get" in the client project:
Resolving dependencies...

Because custom_lint_client depends on repo_lint_rules any which doesn't exist (could not find package repo_lint_rules at https://pub.dev), version solving failed.

The workspace pubspec contains both repo_lint_rules which is a custom lint and the package referring to the custom lint.

Workaround: Use path dependencies for now.

[rrousselGit]

The challenge is that the plugin code isn't part of the workspace.