feat(gatsby): enable babel in deps

[sidharthachatterjee]

This changes our setup to run babel on dependencies in node_modules that use gatsby, during both:

• query compilation
• code compilation

This follows up the work in #15270 and #15179

A follow up to this will include a better (and faster) heuristic when fetching the dependency tree as recommended by @KyleAMathews

[wardpeet]

@sidharthachatterjee this is awesome, just the way I would do it! ❤️
Maybe write a test for the exclude/include mechanism 🤷‍♂ (I can do it in a follow up PR)

[sidharthachatterjee]

Blocked by #15308

[pieh]

🌮

[pieh]

🌮 🌮

[pieh]

🌮 🌮 🌮
(3 tacos's a charm)

[sidharthachatterjee]

Published in gatsby@2.12.1

[ksjogo]

Is there some way to exclude specific folders from this?
I have a monorepo with a basepackage depending on gatsby and providing some config and template components. This package's src/ is pretranspiled via tsc into a lib/ folder.
The concrete gatsby site requires this shared package and should only read lib/
But it is actually reading src/ as well due to it being a package depending on gatsby.
npmignore doesn't help/work here, as the dhared package is symlinked from the site and built in place.