Reenable the livechat cancellation solution

[dzver]

Proposed Changes

This reenables the livechat cancellation solution that was disabled due to Happiness concerns.

livechat_solution was not enabled as a feature and I was presented with an option to either change the if in multiple places or add it as a feature. I decided to add it as a feature.

Testing Instructions

1. Before moving to the p2 with steps for testing with Happychat HUD, keep in mind that in order to see the step, you may need to try a little different cancellation options than what's described in the post. Come back here after completing step 2
2. In order to start livechat, you'll have to follow the steps from pebzTe-sj-p2
3. Make sure Missing Features/Themes shows this:

4. Clicking it starts live chat like this

Pre-merge Checklist

• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-ajp-p2)?

Related to #

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-50992

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-50992&env=jetpack

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.