Support dependency_validator running on analysis_options.yaml files

It is possible, and common practice to add a include: package:<somePackage>/<someEntrypoint>.yaml within an analysis_options.yaml file

For example, this is how pedantic and the newer lints package work

include: package:lints/recommended.yaml

Currently, dependency validator completely ignores this file, but it could, and probably should, audit the dependencies used within these files

I'm proposing the following rules regarding this file:

• if a dependency is used within the analysis_options.yaml include statement and is not declared within the pubspec.yaml file, the command should fail
• if a dependency is only used within the analysis_options.yaml include AND is declared as a non-dev dependency, the command should fail

Start by tracing how dependency_validator reads pubspec.yaml and identifies dependency usage, then locate where analysis_options.yaml files are excluded. Use the include entry in analysis_options.yaml and the dependency declarations in pubspec.yaml as the verification cases. Done means undeclared includes fail validation and dependencies used only by the include are required to be dev dependencies.