feat(yarn2): install node_modules for node-modules linker

[mlavina]

Branching off this comment #795 (comment) because I want to use heroku buildpack with yarn 2 and nodeLinker: node-modules

This is a rough draft to through something up. Will convert to a regular draft when it's ready to be reviewed.

[mlavina]

This should be good to go. This works for my unit tests, but it suddenly started breaking after updating to the latest. I think it's related to #815 but I am unsure.

@danielleadams can you take a look when you have a chance since I based this off your PR? Thank you.

[mlavina]

@edmorley @danielleadams just wanted to conform there is nothing else I need to do with this PR. I didn't find a contributing doc.

I added a new unit test and updated Changelog. I tested this locally with my own project as well and it worked.

[danielleadams]

Thanks @mlavina! Sorry, this week has been a little crazy, but thanks for the PR. I'll try to take a look by EOD

[mlavina]

@danielleadams thank you. Sorry for adding extra work to your plate, haha.

[danielleadams]

@mlavina this looks good, but #819 will change the behavior of the buildpack with Yarn 2 (yarn install will be run by default with the Yarn 2 flags). Once that PR goes in, the buildpack will be set up to more easily use node modules. (Tests are currently failing, but that's what it will look like)

[mlavina]

Should I close this PR in favor of #819 #821 i don't know if this PR does anything different since we are going to run yarn install anyway

[danielleadams]

@mlavina yeah, I think so. Even so, thanks for the work here and feel free to continue the conversation on #821

[mlavina]

closing in favor of #821