fix(react-native-dynamic-app-icon): add exact ipad sizes `152`/`167` for exported icons

[byCedric]

Why

This is an attempt to satisfy Apple's request for dynamic app icons on iPad, using sizes 152x152 and 167x167.

• See: https://developer.apple.com/design/human-interface-guidelines/app-icons#iOS-iPadOS-app-icon-sizes
• See: https://stackoverflow.com/a/70986182

How

• Replaced fixed size and scales with IconDimension
• Added iPad specific icon dimensions, turning on/off based on ios.supportsTablets

Test Plan

• Run example app apps/react-native-dynamic-app-icon
  • iPad support is now enabled
• Verify that iPad icons are exported + registered, and plist contains right icon info