Fix Node 14 for development

[mourner]

Currently GL JS development environment is not compatible with Node v14, which is the current Active LTS version. The dependencies get installed without errors, but running unit or render/query tests produces errors like this:

> ./build/run-node test/unit/geo/lng_lat.test.js 

/Users/mourner/projects/mapbox-gl-js/node_modules/@mapbox/flow-remove-types/index.js:1
SyntaxError: Error parsing /Users/mourner/projects/mapbox-gl-js/node_modules/babylon/package.json: Unexpected token , in JSON at position 726
    at JSON.parse (<anonymous>) {
  path: '/Users/mourner/projects/mapbox-gl-js/node_modules/babylon/package.json'
}

It's not related to babylon specifically, because running render tests points to a different JSON file:

> yarn run test-render

yarn run v1.22.10
$ SUITE_NAME=render run-s build-token testem-ci
$ node build/generate-access-token-script.js
$ CI=true testem ci -f test/integration/testem.js
/Users/mourner/projects/mapbox-gl-js/test/integration/lib/generate-fixture-json.js:1
SyntaxError: Error parsing /Users/mourner/projects/mapbox-gl-js/node_modules/glob/package.json: Unexpected token , in JSON at position 1082
    at JSON.parse (<anonymous>)
    at Object.<anonymous> (/Users/mourner/projects/mapbox-gl-js/test/integration/lib/generate-fixture-json.js:4:14)
    at Object.<anonymous> (/Users/mourner/projects/mapbox-gl-js/test/integration/lib/generate-fixture-json.js:1) {
  path: '/Users/mourner/projects/mapbox-gl-js/node_modules/glob/package.json'
}

Currently I'm not sure what's the issue here, but it might be related to our module loading set up with flow removal, esm and other hooks.

[mourner]

GitHub glitched and duplicated the issue: -> #10290