v5.3.0-alpha.21

Features

• CLI: React-scripts TS template & test (#8451)
• Addon-storysource: Add preset (#8437)

Bug Fixes

• UI: Fix React15 support (#8454)
• Addon-centered: Fix zoom issues for non-Firefox browsers (#8442)
• CLI: Add CRA preset to MDX template (#8452)
• CLI: Add preset-create-react-app to CRA presets template (#8449)
• CLI: Fix CRA-ts fixture package name (#8457)