feat(loaders): deprecate ScheduleContainer BREAKING

[austingreendev]

• BREAKING CHANGE

Description

This PR deprecates the ScheduleContainer found in react-loaders and migrates to the useSchedule hook in container-schedule. This deprecation REQUIRES a BREAKING CHANGE on the Dots and Spinner component where the velocity prop is now a standard duration (in MS).

Closes #147

Detail

With this change it became easier to bring in the work from the next branch rather than start from scratch. This PR now includes all next changes for react-loaders (without the theming improvements).

Timing

This PR should stay queued until we are ready to merge v7

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
• ♿ analyzed via axe and evaluated using VoiceOver
• 💂‍♂️ includes new unit tests
• 📝 tested in Chrome, Firefox, Safari, Edge, and IE11

[coveralls]

Coverage decreased (-0.1%) to 94.481% when pulling f464487 on agreen/loader-hooks into b259ed1 on master.

[austingreendev]

It looks like the ScheduleContainer was never actually exported publicly. I have just removed it rather than following a deprecation path.