Add -all option to 'yarn clean' (#2176)

## Summary:

We've had instances where folks' local repo gets into a bad state. It's assumed that `yarn clean` will resolve this, but it hasn't in all cases because it doesn't delete `node_modules`.

This PR adds a `--all` option to `yarn clean` to demolish all `node_modules` folders in the local repo.

Issue: "none" 

## Test plan:

`yarn`
`yarn clean`
`ls node_modules` # still exists
`yarn clean --all`
`find . -name node_modules -and -type d` # no results!

Author: jeremywiebe

Reviewers: jeremywiebe, SonicScrewdriver, mark-fitzgerald, Myranae, catandthemachines

Required Reviewers:

Approved By: SonicScrewdriver

Checks: ✅ Publish npm snapshot (ubuntu-latest, 20.x), ✅ Lint, Typecheck, Format, and Test (ubuntu-latest, 20.x), ✅ Cypress (ubuntu-latest, 20.x), ✅ Check builds for changes in size (ubuntu-latest, 20.x), ✅ Publish Storybook to Chromatic (ubuntu-latest, 20.x), ✅ Check for .changeset entries for all changed files (ubuntu-latest, 20.x)

Pull Request URL: #2176

utils/clean.sh

@@ -13,11 +13,15 @@ MYPATH=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
 # ROOT is the root directory of our project.
 ROOT="$MYPATH/.."
 
-pushd "$ROOT"
+pushd "$ROOT" >/dev/null 2>&1
 
 rm -rf packages/*/dist
 rm -rf .nyc_output/
 rm -rf coverage/
 rm -rf cypress/
 rm -rf packages/*/*.tsbuildinfo
 rm -rf storybook-static/
+
+echo "Removing node_modules directories. You'll need to 'yarn install' after this."
+find . -name node_modules -and -type d -prune -exec rm -rf '{}' \;
+