Disc 2827 text input2 event handlers

[antoniodangond]

Jira: DISC-2827

Overview:

Adds optional onFocus and onBlur function props to TextInput2.

Screenshots/GIFs:

Testing:

• Unit tests
• Manual tests:
  • Chrome
  • Safari
  • IE11

Roll Out:

• Before merging:
  • Updated docs
  • Bumped version in package.json
    • Breaking change?
      • If it is a beta component run npm version minor
      • If the component is not in beta run npm version major
    • New component or backward-compatible component feature change? Run npm version minor
    • Only changing documentation? All good. Skip this step.
  • After creating a new component, make sure to add it to the Components List in ComponentsView.jsx. To do so:
    • Add a screenshot of the component in docs/assets/img with the format <COMPONENT URL LINK>.png
• After merging:
  • Deployed updated docs (make deploy-docs)
  • Posted in #eng if I made a breaking change to a beta component

[arielzhu1]

🎉 LGTM