Redesign Introduction modal

[SleepySquash]

Resolves #633

Synopsis

Introduction modal has been redesigned.

Solution

Use design from new-design-preview

Checklist

• Created PR:
  • In draft mode
  • Name contains issue reference
  • Has type and k:: labels applied
• Before review:
  • Documentation is updated (if required)
  • Tests are updated (if required)
  • Changes conform code style
  • CHANGELOG entry is added (if required)
  • FCM (final commit message) is posted or updated
  • Draft mode is removed
• Review is completed and changes are approved
  • FCM (final commit message) is approved
• Before merge:
  • Milestone is set
  • PR's name and description are correct and up-to-date
  • All temporary labels are removed

[SleepySquash]

FCM

Redesign `Introduction` modal (#668, #633)

Additionally:
- update PWA iOS home screen icon