Add InteractiveUtils standard library as dependency, and add the tags trait.

[ablaom]

In this PR we:

Add InteractiveUtils standard library as dependency

This allows the implemented_methods trait fallback to be immediately defined in this package (like all the other trait fallbacks) rather than relying on the light/full interface mechanism. The previous exceptional behaviour has been causing me issues in a revamp of the MLJ Model Registry management tools.

(in the light/full switch, some methods do not get sensible overloadings until MLJBase is loaded.)

Of course for users there is no change in behaviour, for MLJBase is always loaded, in which case my changes here have no detectable impact. (In my use case for registry management, I want to inspect trait values without having to load all of MLJBase.)

Add a new tags trait

The name is owned by StatisticalTraits, to which this was recently added. The StatisticalTraits fallback of "", suffices. This trait is intended to have values like ["regression", "gradient descent"] and to be overloaded by model interfaces, to remove the burden of maintaining this database at MLJ docs.

[ablaom]

To do:

Check locally tests for the following downstream packages:

• MLJBase
• MLJTuning
• MLJIteration
• MLJEnsembles
• MLJBalancing Tests currently failing for unrelated reason.
• FeatureSelection
• MLJ (including the integration tests)