feat(pagination): add onChange for pagination component

[debsfong]

• BREAKING CHANGE?

Description

Adds onChange to the pagination component. Currently, onStateChange triggers whenever the pagination component is blurred. onChange will only trigger on changes to the currentPage.

Checklist

• 👌 design updates are Garden Designer approved (add the
  designer as a reviewer)
• 💅 view component styling is based on a Garden CSS
  component
• 🌐 Styleguidist demo is up-to-date (yarn start)
• ⬅️ renders as expected with reversed (RTL) direction
• 💂‍♂️ includes new unit and snapshot tests
• 📒 any new files are included in the packages src/index.js export
• 📝 tested in Chrome, Firefox, Safari, Edge, and IE11

[coveralls]

Coverage increased (+0.009%) to 96.144% when pulling ba20422 on dfong/pagination-onchange into 08c3447 on master.

[ryanseddon]

Thanks for the PR @debsfong can you please add some tests for this change please.

[austingreendev]

@debsfong I just added some tests from our discussion yesterday and also added some a missing prop-types in the Pagination component that isn't related to your change.