Add time taken to add a new module (eg. npm install XXX)

It would be nice if the benchmark also tracked how long it took to install (ie. add) modules, after the project has already been fully installed/initialized.

This is an important consideration, since it's the most common dependency-related operation that is performed (at least in my projects).

It's also significant because npm is actually faster than yarn for adding new modules -- at least for my project, with a package-lock present for both:

These commands were done in order, in the "mobx-devtools-advanced" repo, on 2019-11-13.

NPM version: 6.11.2
Yarn version: 1.19.1

* npm install lodash@1.2.0: 62s (slow since had to clear yarn metadata + rebuild it)
* npm install lodash@1.2.1: 5s
* npm install lodash@1.3.0: 5s
* npm install lodash@1.3.1: 5s
* yarn add lodash@2.0.0: 48s (slow since had to clear npm metadata + rebuild it)
* yarn add lodash@2.1.0: 12s
* yarn add lodash@2.2.0: 10s
* npm install lodash @2.0.0: 67s (slow again due to rebuild)
* npm install lodash @2.1.0: 5s
* npm install lodash @2.2.0: 5s

Note that the operation of just adding a new module took about half as long for npm than yarn.

That said, both are quite fast, so perhaps it's not so important after all.

Start by inspecting the benchmark scenarios and existing npm, Yarn, and pnpm command definitions in the repository. Compare how dependency installation is currently measured, then add a separately reported timing for adding a module after initialization; completion should include benchmark results for that operation.