Support succinct list of updatable deps, and excluding certain deps in an "update all"

[zachsa]

Using the npm-check-updates module, my workflow is typically:

ncu // this prints out updatable deps
ncu -u // update everything

// or 

ncu -u -x typescript // update everything except typescript

It's really nice that we can update importmap deps so easily with this library, extending the API to allow easily seeing what will be updated, and allowing for excluding certain updates in and otherwise 'update all' command would be helpful