[v7] Complete `npm install` command

[mikemimik]

Current Behaviour:

> npm i abbrev taxes undefined
npm WARN deprecated undefined@0.1.0: this package has been deprecated
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN nocommit@1.0.0 No description
npm WARN nocommit@1.0.0 No repository field.

+ undefined@0.1.0
+ abbrev@1.1.1
+ taxes@1.0.0
added 3 packages from 2 contributors and audited 3 packages in 0.734s
found 0 vulnerabilities

We're trying to reproduce this kind of output now that we're using arborist to do tree related things.

• Find the list of added dependencies (one or many), and output them
• Create function to turn arborist tree into an archy tree for outputing

Branches

• https://github.com/npm/cli/tree/mikemimik/feature/npm-install

References

• MINI-EPIC: next steps for v7 integration 2020-03-03 #971