☂️ Improve Typescript support

[patricklafrance]

Description

We did a very good job converting our codebase to TypeScript in the last month before the release of the reboot but we were working against the clock. There are a few areas which could be improved.

This umbrella card aims to provide an overview of the improvements we wish to accomplish.

Related issues

• as prop usage (🚀 Improve "as" usage for TypeScript #515)
• Convert Storybook code (⚙️ Convert Storybook code to TypeScript #552)
• Converto Chromatic tests (⚙️ Convert Chromatic tests to TypeScript #553)
• Convert Jest tests suite (🚀 Convert Jest code to TypeScript #551)
• Add tests for complex types (🚀 Test core TypeScript types #508)
• The as property RFC (🚀 The "as" property RFC #554)
• Deactivate noUnusedParameters in TSConfig (🚀 Deactivate noUnusedParameters in TSConfig #556)
• Update @sharegate/eslint-config-typescript in Orbit to 1.6.0 (🚀 Update @sharegate/eslint-config-typescript in Orbit to 1.6.0 #555)
• Inference in mergeProps parameters is not optimal (🚀 Inference in mergeProps parameters is not optimal #557)