Support --nohoist option for workspaces.

[richburdon]

Feature:

Workspaces currently hoist everything to the root level. lerna supports a --nohoist option to leave modules that match a regex in the packages/sub/node_modules folder.

For example, grunt requires that all plugins are in the local node_modules directory.

[MoOx]

I have this problem when using reasonml packages.
Some of my packages of my workspace require bs-platform + some others other of my own, as deps, but with everything at the root, bsb is throwing some fatal errors like (since you have bsb-platform at the root of the project): Error: Unbound module Pervasives (bs-platform does not like to be relocated).
I tried to add older version at the root of the project so the right version is in the right place for my package and I then got BSB check build spec : Dependencies information missing because some deps are not at the right place for bsb. Using a nohoist glob or something like lerna will make it usable for reasonml packages.

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EDIT: not sure what I did (maybe cleaning all node_modules folder) but I think this entire problem happened because some previous folder where messed up)

[MoOx]

This issue feature request is probably a dupe of #3882

[BYK]

Duplicate of #3882.