Migrate quick start tour to temporary settings storage

Created by: erzhtor

Closes https://github.com/sourcegraph/sourcegraph/issues/35858.

Description

This PR:

• Migrates quick start tour to temporary settings storage to persist state across devices/browsers
• Updates useTemporarySettings implementation to handle all setValueAndSave calls with latest previous value

  // Previously
  const [value, setValue] = useTemporarySettings('my.settings.value')
  setValue(prevValue => ...)
  setValue(prevValue => ...) // here prevValue sometimes is not up to date
  
  // Now
  const [value, setValue] = useTemporarySettings('my.settings.value')
  setValue(prevValue => ...)
  setValue(prevValue => ...) // updated latest prevValue since under the hood it uses React.useState

• Updates useTemporarySettings to return load status:

  const [value, setValue, status] = useTemporarySettings('my.settings.value')
  status // 'initial' | 'loaded' | 'error'

• Adds useObservableWithStatus helper utility which has observable value, loading status and error:

  /* [value, 'initial' | 'next' | 'completed' | 'error', Error | undefined] */
  const [value, status, error] = useObservableWithStatus($observable)

Test plan

• Unit tests updated/added
• Manually test
  • Run sg start dotcom from the main branch
  • Click on quick start tour to make some completion progress
  • Switch to the PR branch and rerun app
  • Make sure progress is still there
  • Also, you check that authenticated quick start tour progress is persistent across browsers when signed in with the same account

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.