Add resolutions to package.json

[bintzandt]

Summary

This PR adds a resolutions section to the package.json in the root of the monorepo.

This resolution forces fsevents to be version 1.2.9, which is the first version of fsevents that adds support for node v12.

You can find more information about yarn's resolutions here.

This PR can be summarized in the following changelog entry:

• [monorepo-root] Force fsevents to version 1.2.9 to add node 12 support.

Relevant technical choices:

• This is a work-around for the real problem, which is that our dependencies are heavily out-dated in some of our packages. Although this PR will allow us to install and build on node v12, we should upgrade our packages to add proper support.

  You can check the release cycle for node here. Node 10 will receive updates until 2020-05-19, after which the maintenance period starts (meaning that serious bugs / security flaws will still be fixed). EOL (End-Of-Life) for Node 10 is on 2021-04-30.

• The tests in yoastseo will fail when using node v12. This is currently also happening in Travis in a test that is allowed to fail.

• I have created an issue for upgrading the dependencies.

Test instructions

This PR can be tested by following these steps:

• Check-out the develop branch.
• Switch to node v12 (I use nvm to do this easily)
• Run yarn install
• Check that it errors on fsevents, although the install will be successful since fsevents is optional.
• Switch to this branch
• Run yarn install (if it says "nothing changed" use yarn install --force)
• No errors 🎉

UI changes

• This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Quality assurance

• I have tested this code to the best of my abilities
• I have added unittests to verify the code works as intended

Fixes N/A

[bintzandt]

Closing this PR because Travis cannot cope with resolutions for Optional Dependencies.