ci: adding eslint rule for polyfills in monorepo

About this pull request

Raised as a result of this comment in this pull request https://bitbucket.org/atlassian/atlaskit-mk-2/pull-requests/7364/ms-2550-check-if-containsnode-is-defined/diff#comment-121061951 . These changes can help us to avoid issues like https://ops.internal.atlassian.com/jira/browse/HOT-88870 in the future, giving browser support feedback in dev loop (Dev Experience ++)

At the total, I got 1236 when I ran the eslint command in AK monorepo, adding all the packages. However, some of the errors are duplicated.

Sharing some points

This won’t fully solve our problems when using experimental features

Since this plugin only checks non-experimental features, this won’t cover some scenarios such as Selection.containsNode() (https://developer.mozilla.org/en-US/docs/Web/API/Selection/containsNode#Browser_compatibility).

However, there are other ways to cover it properly, such as visual/integration/end-to-end tests, add specific polyfills for experimental features in @atlaskit/polyfills, etc.

However, it’s definitely a great start!

With all the polyfills in a list, we can make sure our consumers will have the proper polyfills added on their bundle - perhaps create some automation for it in the future

As a way to mitigate any possible problem, we should revisit the list of polyfills that should be added in our current consumers to make sure our components/experiences are working as expected in all supported browsers